As a born again Christian, and I know I am a newborn, but it really bothers me when people twist religion and do not honestly understand and practice Jesus' teachings. Jesus loves EVERYONE. He does not shun anyone, belittle anyone or make them feel bad about themselves. Jesus would call your son a hypocrite. I think your son is going to have a big wake up call one day...
And I think how you are handling youngest is the right thing to do. He is desperately trying to get a reaction from you. He needs to focus that energy elsewhere - in ways that will enrich his life instead of sitting and wallowing.
(((HUGS)))