A member of the Communist Party of the Soviet Union should:
… be engaged in the uncompromising fight against any manifestations of the bourgeois ideology, against any remains of the private property psychology, religious prejudices and other remains of the past, adhere to the principles of the Communist ethics, and to put the society’s interests over the personal ones.
Chapter 1, Clause 1.d
So a Communist can’t be a Christian or Muslim or else. The only thing he can be is a militant atheist.
I still have a dream. It is a dream deeply rooted in the AMERICAN dream...when all of God’s children, black men and white men, Jews and Gentiles, Protestants and Catholics, will be able to join hands and sing in the words of the old Negro spiritual, “Free at last! free at last! Thank God Almighty, we are free at last!”
~ Martin Luther King Jr.