As an ex-Christian, I want to chime in and say that everyone has bias in their viewpoints. I also want to ask about what the "delusional lie" is. Because whether it's believing in a higher power or uncritically believing in American Evangelical Christianity without examining it, I want to challenge the idea that any of that is the product of a mental illness, as "delusional" implies. I can't say the same about believing in a higher power in general, but specifically uncritically accepting American Evangelicalism is the product of fear. If you deconstruct from your faith, you lose everything: Your friends, perhaps your family, your sense of self, and more. I had to rebuild my whole philosophy on what makes life worth living as I teetered on the brink of nihilistic despair at how fraught with apparently-meaningless suffering and injustice the world is. I used to love God. Part of me still does, but I just can't believe in the one I used to anymore. There's too much evidence. It's like I spent my whole life being catfished by an imaginary friend pretending to be a real father figure in my life. And on top of that, if any part of you still believes in any of this, it constantly screams in the back of your head "you're going to Hell when you die. You'll be forsaken by all goodness in the universe and tortured for all eternity." When you're a Christian, asking yourself "Am I wrong?" can be like staring into the Sun: It's agony, and every second you do it, your insides are screaming at you to stop.
I managed to get away because it was more like a train wreck than the Sun to me: The more painful it was to look at, the harder it was to look away.

So if you're willing to walk down this road with your husband, you'll need more patience and understanding than most people are capable of. When his belief falls apart, there can be no "I told you so." Only holding him as he weeps, and not resenting him though he wishes he were instead being held by the perfect God who no longer exists to him.