In Germany organizations and or parties that promote National Socialism (openly) are illegal per §130 Stgb and Article 9 abs. 2 GG. Reasons are that National Socialism fundamentally is incompatible with the so called liberal democratic order.
In this case why is the ideology of Anarchism and the promotion of it not considered illegal per German law, as it promotes the abolishment of the state?
German gov't can declare a social movement as "hostile to the constitution" by Article 9 of the Basic Law. The Federal Constitutional Court can declare political parties as "hostile to the constitution" by Article 21 (2). This was done in 1952 against the neo-Nazi Social Reich party and in 1956 against the Communist Party of Germany which forcibly dissolved them, prohibited the founding of any successor organizations and withdrew all Bundestag and Landtag mandates, and seized the assets of the parties. It was also tried in 2003 and 2017 against the far-right National Democratic Party, but the constitutional court did not ban it because according to the top judge:
The NPD pursues anti-constitutional goals but at the moment there is an insufficient weight of evidence to make it appear possible that their behavior will result in success
So, if the Federal Constitutional Court determines that any party or social movement like the anarchists are possibly able to succeed in undermining the Constitution/Basic Law or overthrowing German liberal democratic basic order, then they will outlaw it. They can but they don't consider it a threat large enough to proscribe in the constitution specifically, as it had done with Nazism, considering the constitution was written post-WW2 when Germany was national socialist.
You are missing a few relevant laws. Notably §84, §85, §86 and 86a StGB.
§84 and §85 criminalise the continuation of any prohibited party or organisation, while §86 and §86a criminalise the distribution of their materials and usage of their symbols.
Which parties and organisations are prohibited are outlined in Art 21 GG and §3 VereinsG respectively.
They state:
Parties that, by reason of their aims or the behaviour of their adherents, seek to undermine or abolish the free democratic basic order or to endanger the existence of the Federal Republic of Germany shall be unconstitutional.
and
Ein Verein darf erst dann als verboten (Artikel 9 Abs. 2 des Grundgesetzes) behandelt werden, wenn durch Verfügung der Verbotsbehörde festgestellt ist, daß seine Zwecke oder seine Tätigkeit den Strafgesetzen zuwiderlaufen oder daß er sich gegen die verfassungsmäßige Ordnung oder den Gedanken der Völkerverständigung richtet
An organisation may only be treated as prohibited (Article 9 (2) of the Basic Law) if it has been established by order of the prohibition authority1 that its purposes or activities are contrary to criminal law or that it is directed against the constitutional order or the idea of international understanding
This definition could include anarchist organisations. So far, one left-wing 2 organisation has been prohibited under this law. In 2017, the federal government prohibited linksunten.indymedia, an aggregate news site. The decision was controversial but held up in court
One forbidden organisation is not much, but the hurdles are quite high as well. It is not enough for all members of the organisation to want to abolish the FDGO (Freiheitlich Demokratische Grundordnung or "liberal democratic basic order") or commit crimes, the organisation itself needs to have that aim. As anarchists tend to be quite loosely organized with the actual organisations being cultural centers, mutual aid organisations or anti-fascist research groups, there isn't much to go on. There are still a number of anarchists groups mentioned in the yearly report of the Office for Protection of the Constitution, which is responsible for collecting the evidence needed for a probibition. Apparently the evidence is not sufficient to support a full ban. You can read the report (in German) for more information on the various groups that the government is investigating.
This may also be, because the FDGO is more opposed to right-wing instead of anarchist extremism.
In its decision denying the prohibition of the right-wing party NPD, the Constitutional Court set out what the FDGO entails (emphasis mine):
a) The free democratic basic order is rooted primarily in human dignity (Art. 1(1) GG). The guarantee of human dignity covers in particular the safeguarding of personal individuality, identity and integrity and elementary equality before the law.
b) Furthermore, the principle of democracy is a constitutive element of the free democratic basic order. The possibility of equal participation by all citizens in the process of forming the political will as well as accountability to the people for the exercise of state authority (Art. 20(1) and (2) GG) are indispensable for a democratic system.
c) Finally, the concept of the free democratic basic order is further determined by the principle that organs of the state be bound by the law (Art. 20(3) GG) - a principle which is rooted in the principle of the rule of law, and by independent courts’ oversight in that regard. At the same time, protection of the freedom of individuals requires that the use of physical force is reserved for the organs of the state which are bound by the law and subject to judicial oversight.
Anarchists tend to support human dignity, they tend to support the principle of democracy (although they tend to promote different implementations than liberals). The only place where they oppose the FDGO would be with regard to the rule of law and the state monopoly on violence. Importantly, a monopoly on state violence does not mean that the state must be violent. It would be perfectly within the FDGO to eliminate all state violence, as long as no other violence takes its place. It is up to you, whether you believe that to be possible but if anarchists do, they do not violate the FDGO.
Also, an anarchist organisation would have to actually organisationally work against the FDGO to be a candidate for prohibition. It is not enough that many of its members want to achieve that goal, unless they use the group to organise to that specific effect. Front-facing anarchist organisations are focussed on things like legal support for protestors, labour unions or mutual aid networks (as mentioned by Simon Richter), all of which aren't actually unconstitutional. The dubious stuff that might actively oppose the FDGO tends to happen in smaller, unorganized groups.
A note on §130 StGB
§130 is a separate law, specifically against hate speech, which in Germany explicitly includes praise of the Nazi regime or denial of its crimes.
However, subsections 1 and 2 deal with calls for violence or grave insults against racial, national, ethnic or religious groups in general, while subsection 5 deals with genocide denial in general, so the prohibition does not exclusively target Nazis. Also, it does not stop you from joining Nazi groups, as long as you keep that involvement to yourself.
Also, §130 StGB is not there to protect the Freiheitlich-Demokratische Grundordnung (FDGO, the liberal democratic order mentioned in the question). Instead the protected good is the dignity of the targeted people. As such, there is no prohibition against publicly calling for the establishment of a dictatorship or the abolition of the entire state. Such statements would only be illegal under §130 StGB, if they also included attacks against the aforementioned groups.
Prohibited speech by anarchists is unlikely to fall under that, because even violent anarchists tend to pick their targets on the basis of their political alignment, occupation or wealth and not on the basis of race or religion. Anarchist speech is more likely to fall under §140 StGB which prohibits publicly praising violent criminal acts.
There are also §80, §82, §83 StGB, which deal with treason and the usage of violence to abolish the constitutional order or inhibit the existence of a state.
And §105 and §106 StGB which deal with violence or threats of violence used to compell action or inaction from a constitutional body or members thereof. The latter would deal with things like a bomb threat on the Bundestag to force its members not to vote for a certain law.
These could also apply to anarchists, especially if they use violence to abolish the state. However, it is unlikely that anarchists are convicted under any of these (except for §106, which applies to individual people), as the courts have a narrow definition of violence against constitutional bodies.
In particular, the BGH (which is the highest criminal court in Germany) swrote the following in its decision BGHSt 23, 46 (regarding blockades of tram lines in 1966):
Das Urteil darüber, ob ein tatsächlicher Vorgang als Gewalt im Sinne eines bestimmten strafrechtlichen Tatbestandes anzusehen ist, läßt sich nicht einfach dadurch gewinnen, daß dieser Vorgang an einer abstrakten Umschreibung des Gewaltbegriffs gemessen wird. Solch isolierte Betrachtung ist verfehlt; der Vorgang ist stets im Zusammenhang mit dem vom Tatbestand vorausgesetzten Ziel des Handelns und in seinem Verhältnis zu der Person oder den Personen zu beurteilen, die betroffen oder beeinflußt werden sollen. Es genügt also nicht, daß eine zur Überwindung irgendeines Widerstandes geeignete Kraft entfaltet wird, sondern es kommt wesentlich auf die spezifische Eignung dieser Kraft im Sinne ihrer vom Tatbestand vorausgesetzten Wirksamkeit an.
The judgement as to whether an actual event is to be regarded as violence in the sense of a specific criminal offence cannot be made simply by measuring this event against an abstract description of the concept of violence. Such an isolated view is misguided; the act must always be judged in connection with the objective of the action presupposed by the offence and in its relationship to the person or persons who are to be affected or influenced. It is therefore not sufficient that a force suitable for overcoming any resistance is deployed, but it is essentially a matter of the specific suitability of this force in the sense of its effectiveness presupposed by the offence.
This horribly convoluted piece of legal writing basically says that acts against constitutional bodies have to actually be able to affect these bodies to be considered violence. Torching cars or even attacking some police officers would not be enough to constitute violence against the constitutional order, the scale is too small. Of course, torching cars or attacking police officers are crimes(§306 and §114 StGB respectively), just not crimes against the constitutional order. German anarchists are nowhere near the level where their acts would actually threaten the constitutional order.
1: The prohibition authority is the federal ministry of the interior or the equivalent agency in one of the states. the decision can be appealed at an administrative court.
2: Anarchism is more complicated than a left-right distinction, this answer will talk about left-wing anarchism. The closest thing to right-wing anarchists would be the so called "Selbstverwalter" (sovereign citizens). However, in Germany, they are closely linked to the Reichsbürger movement which is decidedly authoritarian and wants a return to the German Empire.
As a German anarchist: we are very democratic, and fairly realistic about how most people are not capable of self-organization in the absence of a strong state that curtails their freedoms for the greater good. Abolition of the state can only be achieved through consensus, and such consensus can only be achieved if the drawbacks of being organized as a state outweigh the benefits.
Anarchist organization against the state thus consists of building mutual aid networks that reduce the utility of the state.
The state does, quite heavy-handedly, oppose efforts to self-organize, and police will often raid soup kitchens or womens' shelters if they are not attached to an organization that is visible to and integrated with the state, because they would prefer a less democratic, less mutual and more controllable distribution of aid.
It is however difficult for the state to argue that replacing the state with more democratic and less centralized structures is an anti-democratic act, and the drafters of the basic law were not overly concerned with that either, quite the opposite: what the state needs to protect itself from is capture by anti-democratic forces.
The paragraphs you quote is one line of defense here, assuming working democratic institutions and giving them the necessary legal standing to be proactive.
The basic law also provides a fallback if democratic institutions fail, preemptively legalizing a (possibly anarchist) uprising under rather narrow conditions that we all are working hard to avoid.
In Germany you have Meinungsfreiheit (freedom of opinion):
(1) Every person shall have the right freely to express and disseminate his opinions in speech, writing and pictures and to inform himself without hindrance from generally accessible sources. Freedom of the press and freedom of reporting by means of broadcasts and films shall be guaranteed. There shall be no censorship.
(2) These rights shall find their limits in the provisions of general laws, in provisions for the protection of young persons and in the right to personal honour.
So in general the line of reasoning is NOT that certain ideologies are illegal. The line of reasoning is that freedom of expression finds its limits if you violate the law and/or the rights and freedoms of other people.
So if you read §130 StGB (German penal code) carefully you'll see that this actually refers to "incitement of the masses"
(1) Whoever, in a manner suited to causing a disturbance of the public peace,
- incites hatred against a national, racial, religious group or a group defined by their ethnic origin, against sections of the population or individuals on account of their belonging to one of the aforementioned groups or sections of the population, or calls for violent or arbitrary measures against them or
- violates the human dignity of others by insulting, maliciously maligning or defaming one of the aforementioned groups, sections of the population or individuals on account of their belonging to one of the aforementioned groups or sections of the population
incurs a penalty of imprisonment for a term of between three months and five years.
So the main point isn't about abolishing national socialism as much as protecting the "inviolable right to dignity" explicitly stated in Article 1 of the German constitution.
(1) Human dignity shall be inviolable. To respect and protect it shall be the duty of all state authority.
(2) The German people therefore acknowledge inviolable and inalienable human rights as the basis of every community, of peace and of justice in the world.
(3) The following basic rights shall bind the legislature, the executive and the judiciary as directly applicable law.
Now how you'd do fascism without demonizing an other, idk, but that is their problem, not one of any law abiding citizen.
Now to be fair subsections (3) and (4) directly target disturbing the public peace by (3) downplaying nazi crimes or (4) glorifying the nazi reign, but again neither targets any ideology explicitly. Of course talking about "a great nation in decline" and how previously "everything has been great before the degeneracy of the democratic system" and other fascist tropes, is a tough sale with the Nazis and WWII in the history books, but there are few historic fact more established, researched and corroborated by evidence.
So if you have to value the dignity of the victims of the Nazi crimes against Neo-nazi aspiration to lie about history, well Germany made a rather obvious decision.
On top of that §86 and §86a StGB specify the dissemination and public display of propaganda material of parties who received a final verdict of being unconstitutional. Which obviously famously applies to original Nazi party NSDAP as well as their sub-organizations.
That's why you can't do Hitler salutes, show swastikas or whatnot. Though that is also just meant for their usage for promotional usage or lack of context, whereas "to prevent unconstitutional activities, to promote the arts or science, research or teaching, reporting about current or historical events, or similar purposes." is not a crime. So history books and non fascist documentaries and whatnot might still show original footage or whatnot without going to jail.
Now Germans also have a right to assemble.
Article 8 [Freedom of assembly]
(1) All Germans shall have the right to assemble peacefully and unarmed without prior notification or permission.
and a freedom to associate and form groups and parties:
Article 9[Freedom of association]
(1) All Germans shall have the right to form societies and other associations.
(2) Associations whose aims or activities contravene the criminal laws or that are directed against the constitutional order or the concept of international understanding shall be prohibited.
So (2) forbids associations with the goal to do criminal stuff or overthrow the constitution. You still have freedom of opinion though, that is just getting into practical matters.
On top of the mere association you can also form political parties:
Article 21 [Political parties]
(1) Political parties shall participate in the formation of the political will of the people. They may be freely established. Their internal organisation must conform to democratic principles. They must publicly account for their assets and for the sources and use of their funds.
(2) Parties that, by reason of their aims or the behaviour of their adherents, seek to undermine or abolish the free democratic basic order or to endanger the existence of the Federal Republic of Germany shall be unconstitutional.
(3) Parties that, by reason of their aims or the behaviour of their adherents, are oriented towards an undermining or abolition of the free democratic basic order or an endangerment of the existence of the Federal Republic of Germany shall be excluded from state financing. If such exclusion is determined, any favourable fiscal treatment of these parties and of payments made to those parties shall cease.
(4) The Federal Constitutional Court shall rule on the question of unconstitutionality within the meaning of paragraph (2) of this Article and on exclusion from state financing within the meaning of paragraph (3).
(5) Details shall be regulated by federal laws.
Which are more established organization with rights and duties, that are required to be internally democratic and which must not seek to undermine the "Freiheitlich Demokratische Grundordnung" (liberal democratic basic order, though liberal in the sense of concerning individual liberty not some economic liberalism) or endanger the state itself. If they do, their funding and favorable fiscal treatment is discontinued and their name symbols or whatnot become subject to §84-§86a StGB (continuation despite ban, forming of a successor despite ban, propaganda, usage of symbols).
Which apparently also includes the successor to the NSDAP the SRP and the communist party of Germany KPD, which technically also means that the KPD letters as well as the hammer and sickle are banned. Though practically it's really weird (German source), because apparently since the Democratic Republic of Germany joined the Federal Republic of Germany, with all their parties and organizations (including the KPD which together with the SPD formed a new party the SED), there's now both a legal and an illegal KPD, also as hammer and sickle are also symbols used world wide without reference to a particular German party only the usage in that particular context is illegal.
So again it's not the really any particular ideology that is banned but rather concrete crimes and organizations with the aim to commit crimes. Though to be fair given that democracy is a pretty leftist concept to begin with Neo-Nazis are just more prone to violate the law in general and avoiding to violate the law would almost require them not to be National Socialists, which is fully intended, but doesn't require a specific ideological ban.
On the other hand Anarchism, so the idea that nobody should rule over other people, simply doesn't have much of those intrinsic problems. So inciting racism, sexism, homophobia, xenophobia and so on simply isn't part of the anarchist agenda and would actually violate their own principles before violating the laws.
Also as anarchists often have a problem with rigid organizational structures, those bans on parties and clubs are way less likely to affect them, in that regard as they don't usually organize as such in the first place.
There are organizations like anarcho-syndicalist unions like the FAU, but as long as they are busy doing union stuff and don't try to overthrow the government, they are on the radar of the Verfassungsschutz (police tasked with the protection of the constitution) but they aren't necessarily an immediate necessity to intervene.
So what is more likely is that individuals are arrested for crimes outside of the political movement or for violations of laws due to acting outside of the legal context. But as long as there's no revolutionary violence the state is suspicious of them and count them as left-wing extremism due to their tendency to so radically being in favor of democracy that they would ultimately also are antagonistic to the state itself, but unless that cannot be tied to actual crimes, it's not illegal per se.
Also there's the distinction between anti-constitutional and unconstitutional where it's within your freedom of opinion to be against the constitution, as otherwise you'd never be able to change it, that being said, there are legal ways to change it and going outside of that framework marks something unconstitutional and thus subject to the criminal law, including bans and whatnot.
So TL;DR Anarchists are less likely to violate the law (with regards to human dignity and being against freedom and democracy (on the contrary)), and where they violate the law they usually aren't organized in criminal organizations that can be effectively banned. Sure some "Autonome" may be linked to petty crimes and vandalism, but that's not really the "effective aim to dismantle the state" or "incitement of violence and disturbance of the public peace" or if their effective means to dismantle the state involve demonstrations, educating about democracy and practicing democratic forms of organization, then the goal might be problematic but all of the actions are perfectly legal, even explicitly allowed in the constitution and often encouraged in a democratic system. So where even neo-fascist organizations are granted those rights with the benefit of the doubt, before proving they are unconstitutional, it's hard to argue in that direction.
And even where it militant you need to link them to a specific project that you want to ban, otherwise you can only target the individual not the collective.
Realistically, the main reason it seems that way is simply that anarchism has never been a mass movement or perceived as a threat to the German state, at least in the second half of the 20th century. Whether it is compatible with the “liberal democratic order” is not merely an academic question for the state. It's mostly used to justify expanding resources fighting it (intelligence and police surveillance, legal proceedings) and curtailing public liberties.
Furthermore, the main concern of the framers of the German “Basic law” was to protect the electoral system based on the notion that the Nazis were able to use the institutions of the Weimar Republic to come to power. Anarchists do not typically engage much with electoral politics so preventing them from partaking in elections is not a priority.
On the other hand, it is not the case that the German state has been exclusively or primarily concerned with fighting (neo-)nazism. In particular after banning the Sozialistische Reichspartei in 1952, the focus quickly moved to the communist party (KPD). Its ban in 1956 was followed by the seizure of party property, the closures of many organizations deemed affiliated with the party, numerous investigations and a purge of the civil service.
On a lower level, anarchism and the “autonomous scene” are certainly within the scope of surveillance by the Federal Office for the Protection of the Constitution or everyday police repression, together with Islamists and Kurdish and Palestinian organizations (Auslandsbezogener Extremismus).
