Jerusalem is a holy site for three major religions: Judaism, Christianity, and Islam. This is the reason that Israelis and Palestinians both want to live in Israel and are constantly in conflict. Jerusalem is a place that sadly has many clashes between cultures, including stabbings and even murders. As one of the most contentious places in the world, it is the worst possible place to move the US Embassy. An embassy is supposed to act as a safe haven for those who need protection. If it was moved to Jerusalem, it would constantly be in danger and could even lead to a riot or a full civil war.
Right now, the embassy is in Tel Aviv, a place that's a safe distance from Jerusalem and that has relatively little conflict. There is absolutely no reason to move the embassy except to create conflict. President Trump wants to move the embassy to fulfill his campaign promise, but like many of his campaign promises, it's best not followed up on.
If one has any knowledge of the Israel-Palestine conflict, it is clear that it makes no sense to move the embassy to Jerusalem. And to add insult to injury, Trump also announced Jerusalem as the capital of Israel. This is an even worse move then moving the embassy (if possible) because Israelis and Palestinians fight over who Jerusalem belongs to.
When I say a civil war is very possible, I'm not just being paranoid. After Trump's speech about Jerusalem being the capital of Israel, Palestinians began to clash with Israeli forces. There are protests in the streets, there is tear gas, Hamas calls for the beginning of a third intifada. The President is causing riots and havoc in a country on the other side of the world.
Some people are saying that Jews are happy about this, but as an American Jew I can tell you I'm not. Most people don't want Jerusalem to be the capital badly enough to suffer violence and possibly even a war to get it. Trump's announcement could have catastrophic consequences, but only for people that he lives a very safe distance from.
Trump should take back what he said, before more damage is done.