Lenin on The Attitude of the Workers’ Party to Religion:
The proletariat in a particular region… is divided, let us assume, into an advanced section of fairly class conscious Social Democrats [the name used by socialist groups in Russia], who are of course atheists, and rather backward workers…who believe in god, go to church, or are even under the direct influence of the local priest… Let us assume furthermore that the economic struggle in this locality has resulted in a strike. It is the duty of a Marxist to place the success of the strike movement above everything else, vigorously to counteract the division of the workers in this struggle into atheists and Christians, vigorously to oppose any such division. Atheist propaganda in such circumstances may be both unnecessary and harmful—not from the philistine fear of scaring away the backward sections, of losing a seat in the elections, and so on, but out of consideration for the real progress of the class struggle, which in the conditions of modern capitalist society will convert Christian workers to Social Democracy and to atheism a hundred times better than bald atheist propaganda.
We must not only admit workers who preserve their belief in God into the Social Democratic party, but must deliberately set out to recruit them; we are absolutely opposed to giving the slightest offense to their religious convictions, but we recruit them in order to educate them in the spirit of our program, and not in order to permit an active struggle against it.