[A_perfect_lady]

For Chambers, the “crux of this matter is whether God exists. If God exists, a man cannot be a Communist, which begins with the rejection of God. But if God does not exist, it follows that communism, or some suitable variant of it, is right.”

Nonsense, why would those be the only two options.

[ProtectOurFreedom]

It is a reasonable postulation. God either exists or not. It is binary.

If God does exist, a man cannot be a communist.

If God does not exist, man will exalt the state to the same level as God. Power hungry men will demand they be revered as God and control everything you are. Look at every communist state - NORK (Kim dynasty), China (Mao), USSR (Lenin, Stalin, et al).