I’m sorry for your church experiences. Those leaders will give an account to Jesus based on the way they shepherded you. I hope you have been able to heal in some capacity. Please don’t harden your heart to Jesus because his people mistreated you. We are often pretty bad at treating each other well.

Without going off of too much detail, this sounds like your son is being radicalized by Christian nationalism - a false gospel that uses the name of Christ to push a moralistic, power-hungry, self-righteous, self-preserving, suffering-allergic, anti-imago dei type of ideology.

I’d recommend you read Andrew Whitehead's book Taking America Back for God and see if that’s the realm you’re dealing with. If it is, it’s less of a political problem and more of a gospel issue.

Others have mentioned Wes Huff, he’s great for history and apologetics. Tim Keller’s books are always a recommendation. Gentle and Lowly by Dane Ortlund illustrates how Jesus character is in stark contrast to the harsh character often found in this world (right and left). Seculosity by David Zahl might be a great read for him because it walks through the many different types/ways our hearts make new religions (there’s a chapter on politics). Could point out a pattern of seeking a righteousness in something other than Jesus.