I get the idea that you think Trump is a faithful Christian... I mean, dude, just look at his life - he's divorce multiple times. And people are not looking up to him as a spiritual leader. People elected him to do a job, get rid of all the frauds, all the illegals, controlling the economy, etc. etc.
He did it to mock Pope Leo... who is a big critics of the fighting with Iran. Only Catholics look up to the Pope... Christians do not.
Remember when Trump posted himself as a Pope after the Pope Francis die? Same sort of thing...