No, I think it is you that misunderstands.
Evangelicals and fundamentalists (as regarding which, I am not one), surely, do not generally approve of Donald Trump’s behavior.
However, he has frequently spoken words and instituted policies with which they strongly agree.
More importantly, he has made many federal-court nominations–and not just to the SCOTUS, either; it gets all the attention; but lower federal courts often decide an issue, which never is taken up by the Supreme Court–that evangelicals and fundamentalists find appealing.
So one must ask oneself the question: Is it worthwhile to have a person in the White House who seems hypocritical, when he (perhaps ostentatiously) appropriates to himself the symbols of Christianity–but who institutes policies, and makes federal-court nominations, that could have a long-term impact that most evangelical and fundamentalist Christians will find appealing?
But some people simply wish to influence evangelicals and fundamentalists, to sit on their hands in November–or even to vote Democratic–and therefore such people ignore these complicating issues…