How would you feel about an islamic community here?

To rephrase Stalin, there is the dogmatic way to do Marxism, and there is the pragmatic way. We follow the pragmatic way. I think we ought to entertain a network where everyone is welcome as long as they are friendly to the Marxist-Leninist cause and do not seek any trouble.

That being said, religion is often manipulated and corrupted when intermingling with political economy by organising itself into churches, sects, cults, and affiliated marketing schemes. Depending on their historic tendency to exert pressure against the economic welfare of the proletariat, to intrude upon the orderly proceeding of science and statecraft, to involve themselves in offences against the common good and the dealings of the criminal underworld, and to peddle anti-communist hysteria, the role of predatory religious organisations is to be shunned, and in particular clearly distanced from the genuinely progressive, proletarian aspect of the faith.

as a Muslim I often feel very alienated by militant atheists in Socialist circles it's so strange

I just ignored one community like this, it had community banner with Marx of all people saying only the god is lord of the land. I get that this is a joke about landlords but still in very bad taste.

There Christian based ones, and witchcraft ones. Why not?

I once spoke about astrology and everyone lost their shit. We should respect everyone's views so long as they're not against our community guidelines as a whole. The obvious no racism, misogyny, etc.