Question

Why did the USSR adopt atheism as an official state policy?

Answer 1

I am pretty sure that the reason whythe USSR adopted atheism as an official state policy is being revealed by the option :  to eliminate one potential source of conflict and opposition. Lenin set an aim which would make people believe in ideas followed by communism and he thought that religion could pose as an obstacle for socialism.
Hope it will help you!

Answer 2

The first answer is correct (A).

The USSR was officially atheist since Soviet socialism had a Marxist-Leninist orientation. That is a perspective points to two causes of opposition to religion, scientific socialism, and manipulation of the working class promoted through religion.

After a period of tension between the power of the Soviet state and the Orthodox churches, the churches were persecuted and had their properties confiscated. The excuse was the division of wealth of the church among the population, but the central element was the cleavage of any power conflict with the church.