Marx's maxim has been reversed: it's now atheism that is the opi(ate) of the people, the idea we are not ultimately accountable for our actions.
"Atheism is not merely the denial of a dogma. It is the reversal of a subconscious assumption in the soul..." - Chesterton
"We do not really face two rival versions of Christianity. We face Christianity on the one hand and, on the other hand, some other religion that selectively uses Christian words, but is not Christianity." - J. Gresham Machen