I've read people making the argument that because Trump is a 'good' president what happens in his private life or happened before does not matter. That kind of thinking is what stopped King David, also considered a good king, from being able to build the temple and having to go to war with his own family.
Can we still make the argument that he is Christian if his life does not reflect that? I get it that a person can make mistakes and stumble, but Trump seems to be stumbling very regularly. Faith is not just saying that you believe something, it requires action and obedience according to the book of James.