Cruz wasn't booed when he said, "Tonight, we are all united in defense of Jews." He was applauded. He was booed when he said, "Christians have no greater ally than the Jewish state," perhaps because the audience disagreed factually with the statement or perhaps because they thought he was going to make his speech about Israel rather than persecuted Christians.
I agree that it wasn't just Muslims who were booing and that Arab culture is different from Western culture, but a lot of people in the world don't feel about Israel exactly as Ted Cruz does, and that's not a matter blanket disliking or hating, but of feelings that can be quite complicated.
Cruz was responding to the hate-filled speeches before his (he was last), he changed his statements to counter those messages.
I don’t know this group but I have doubts there are actually Christians in it.