The correct form is "Whom would Jesus have bombed?"; since Jesus was a first-century Jewish nationalist, the most likely answer is, "The Roman Empire."
"Who would Jesus bomb?" was undoubtedly inspired by "What would Jesus do?", a question best answered by "We'll never know. Jesus wouldn't have gotten himself into the mess you're in."
The phrase points out the obvious hypocrisy of Christians who support wars, particularly those wars that bomb innocent civilians and create a great deal of collateral damage.
The logic works as follows;
1) Jesus was a pacifist, and taught his followers to be as such. ("turn the other cheek," "love thy enemy," etc.)
2)Christians live by the teachings of Christ.
3)Many, though not all, Christians are the first to support the invasion of other countries, and are, therefore, not acting in a pacifist manner.
4)These Christians are in direct contradiction of the teaching's of Jesus.
5)These Christians (the war mongering Christians) are hypocrites.
In a word, the rejection of war-mongering Christian Conservatism.