Is religion cause of most wars?

[Minimalist]

and trying to make his country atheist

He wasn't trying to make it atheist.  He was trying to make it communist.  Or at least "collectivist."

I think you are confusing your commies, C/L.

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.

V. I. Lenin

The Bolsheviks confiscated all church property within the first two years of the revolution.  This was long before Stalin arose.