I am the son of a fundamentalist minister. For a time, I was also a Christian. I'm now an atheist.
Take it from me: you're wrong. I've been there. There is literally nothing you can say to them. Their belief system is invested in it not being true. It's like the quote attributed to Upton Sinclair: 'It is difficult to get a man to understand something, when his salary depends on his not understanding it.'
I once stood in my doorway and pitied Einstein et. al, smugly thinking that for all their "human wisdom", they weren't able to grasp these "universal truths of God as made manifest through creation." Me, who dropped high school physics. So you see, there's another element to the denial. It allows less intelligent people to think they have something over "these intellectuals."