Personally, I was surprised to find out that Trump had thought about religion at all. He just does not seem to be the type.
But, I will also say that one of the things that allowed me to enter back into the Church was to realize that the Church is really more like a spiritual hospital for sinners than it is a museum to the saints, and that those inside the Church were sinners hoping for healing, not hypocrites cynically using the Church for status. It is possible that he seeks God in private, while consistently struggling to live the life. Is it likely? I don't know. It is possible, though.
I will say that I am more likely to believe that someone believes but fails to resist temptation to sin (as with sexual sin) than I am to believe that someone believes in Church Doctrin, but consistently supports laws that oppose Doctrine. The former is succumbing to temptation; the latter is just outright opposing in public life that which the Church teaches.
Link: https://www.cnn.com/2016/10/21/politics/trump-religion-gospel/