Countries which have laws ensuring the right of freedom of association can't ban any organisation and so it can't ban organised religion. How could you force such a ban? if more than 3 people of the same religion get together is that an illegal association and thus you would be arrested? Would you have to register everyone's religion so that you could know if a gathering was for the purposes of organising for religious reasons? Would religious publications be banned? This impinges on freedom of speech.
Essentially a ban would be counterproductive. It would cause religious people to feel oppressed and suppressed, which of course generates ill-will towards a society that seeks to restrict their right to free association and free expression. This would lead to underground organisation, which would be a violation of anti-organisation laws, which ipso facto makes these people criminals. This would lead to arrests and prosecutions, leading to even more entrenched feelings of suppression and persecutions, which would lead to plots to fight back against oppression and ultimately to acts of religious violence on a larger scale than has been seen. As an organisation that is unlawful by definition there would be no constraints around promoting aggressive action against things like abortion. Since you are already a criminal organisation there's no reason to appear to be not so extreme about things.
Religious oppression has always ultimately failed.
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
"When the power of love overcomes the love of power, the world will know peace."
Jimi Hendrix







