Because the Christian apocalypse requires the foundation of Israel. The Christian side is basically participating in an apocalypse cult, whether they realize it or not.

I speculate that the reason the GOP is so supportive of Trump is because they believe he's the literal Antichrist and they think that getting him reelected will bring about the end of days. I don't have the link on me (though someone else might), but I remember reading an article by a Christian scholar or something about how Trump nailed every possible prophecy about the Antichrist that he could, either in a literal or metaphorical sense, during his presidency. Now, I personally thought some of them were stretching it, but it was still a bit freaky and made me consider the possibility that the GOP actually believes something like that.

The funny/sad part is that if they truly are correct (I highly doubt it, but ehhh...), then that means they'll be fucked alongside Trump due to their support of him. As far as I can remember, the Bible doesn't give amnesty to the Antichrist's supporters just because they believed they were "helping god"; if anything I think I remember the Bible saying the opposite (don't try and force God's hand or you'll eventually face his wrath).

(No, I'm not a Christian, but I still find it fascinating and mildly concerning)