Your premise is faulty and without objectivity, as Israel wages no war against Gaza or the Palestinians. The war is against a terrorist thuggery, as is ISIS and the rest of the Islamist Zealots who would bring a theocracy to the world.
That your question is either predicated upon ignorance or based on a theistic bias and hatred of a free society.
Israel fights against tyrannical rule, against a people who value nothing save the conquest of civility and decency for the benefit of terror. They are as maundering gangs of thugs, as one might find on the Streets of Chicago, blind to all things, but the cause of supremacy.