Pompeo's pre-taped speech from Jerusalem tonight is noteworthy for a lot of reasons, but especially the audience. You might think that giving a speech from Israel, the Jewish state, is designed to appeal to Jews, but it's actually a very clear signal to many white evangelical Christians, who see the modern state of Israel as the fulfillment of biblical prophecy. According to that prophecy, God promised the land of Israel to the Jews, and the Jews' return to Israel is part of the prophecy surrounding the rapture and the second coming of Christ.
To give you a sense of how widespread these beliefs are, a poll conducted in December 2017 by Lifeway Research, a Baptist polling firm, found that 80 percent of evangelicals (note: the definition of "evangelical" they use is fairly specific and different from most other pollsters) believe the existence of the modern state of Israel fulfills prophecy about the second coming of Christ. During Trump's presidency, decisions like moving the U.S. embassy to Jerusalem have also been touted by some evangelical supporters as fulfillments of that prophecy.