I agree with you about Trump's relationship with Christ. Nothing is clear except what he says. Who am I to judge?
It would be more revealing if someone like Franklin Graham did an interview with Trump, someone that Trump does not feel is out to get him like the news media tend to be. I could pass over Trump’s wisecrack about forgiveness (that he tries to do things not needing forgiveness) in the context of Trump’s coyly not wanting to give the media another gotcha on him. But that leaves the question unaddressed. And Trump has seemed to learn on the level of leaving some old positions, which would imply a kind of repentance.
Trump may be just barely a believer.