The minister of the church Trump's family attended was Norman Vincent Peale. Peale was the author of the book The Power of Positive Thinking. He was also one of the early national radio and TV evangelists along with Billy Graham, Oral Robert's, Fulton Sheen, etc.
What Trump learned from Peale was "believe in yourself" which I believe Trump translated to Me First. That is his true faith, The Church of Trump.