Trump says he is a Christian.
If you want to argue that he is not a good Christian, I suppose you can do that. It would be tough to argue with that.
If you want to say, "He's not a real Christian," citing the standards that in your mind constitute somebody's being a "real Christiantm," then you can certainly do that.
But as far as I have been able to determine, individuals in this country continue to be allowed to define their beliefs as they see fit, no matter how many of us wish to insist that those persons don't cut the mustard to be one of the specific group to which they are claiming affinity. See also: Richard Nixon was a Quaker.
That said, I think he is a very poor representative of the broad group of Christians and makes them look worse.
Well that is your opinion on good or bad Christian.
The operative word is Christian.
Being Christian is not a word. It is a way of life in which actions implement compassion, tolerance, temperance, peace and love towards others. All Trump has is the word, and the false swagger of a greedy and venal man. He does not follow Christ.