1) Bush's speech implies that as long as Arafat is calling the shots, then Israel has every right to defend itself by all means necessary.
2) By ending his speech with the bible quote, he is telling the Muslim world that "we know what your ultimate goal is and we will not let the Christian world be taken over."
I'm not always a Bush supporter, but this sounds like it was equally balsy as his post-9/11 speech.