Okay, here is a short diary.
(1) all human beings are of equal value
(2) we should gauge our actions based on what has the best consequences for human beings( I don't want to get into animal rights, which is an important subject, for now)
(3) war is justified only if the consequences for those human beings concerned (including future human beings) is over all better than if there was not such a war
Ergo, almost all wars in human history, and specifically the war in gaza, are morally unjustifiable