That's not what he said. The tweet did not call Trump "The second coming". He was talking about how some in Israel feel about Trump, and used a hyperbolic example to get that point across. Trump retweeted it for the high praise, obviously.
The joke however, was him sarcastically looking to sky and claiming he was "the chosen one". It was a shot at it taking so long for someone to come around and challenge China on trade. It wasn't a serious blasphemous claim, like some insane people in here are pretending to believe it was. Anyone can see he was being facetious. Anyone but the TDS crowd, anyways.