Calling Hell is the Absence of God a critique of religion misses the point. Chiang isn’t saying “religion is false.” He imagines a world where God’s existence and Heaven and Hell are undeniable, and shows that even certainty doesn’t solve the problem of suffering or the struggle for meaning. The story critiques the idea that proof would make faith easier, not religion itself.

I've not read the book but beating this whole thing left and right in my head, I've come to a similar conclusion. It's pleasantly jarring to hear that Chiang (whose other works i like very much) had a similar position.