Gino Cerutti
Italian
This is not true at all. From "About the attitude of the working party toward the religion" by Comrade Lenin:
"Religion is the opium of the people: this saying of Marx is the cornerstone of the entire ideology of Marxism about religion. All modern religions and churches, all and of every kind of religious organizations are always considered by Marxism as the organs of bourgeois reaction, used for the protection of the exploitation and the stupefaction of the working class."
Marxism and atheism are absolutely inseparable.
He is an atheist. In "Comandante", which can be viewed in its entirety, free of charge, on YouTube, he claims to have never been a believer.
Castro's thought about religion is particular and it isn't very clear:
Catholic.net - FLASHBACK: 2006 story Castro and the Church