Most wars might not be about religion, but the winners of wars invariably assert their religion over the vanquished. Its not two armies having a go at each other, but "plague of the firstborn" is pretty religious.
BTW, lots of your "non religious wars" have strong religious elements. The Korean war was between the largely Christian, western backed south, and the largely irreligious/personality cult north, where Christians are persecuted.
Rome and Carthage fought many wars, the later ones involving the Vandal Kingdom of Carthage and Rome where largely fought over the Arian Christian Vandals oppressing the Roman Catholic locals. The whole of Roman Africa and the Levant were overran with the Muslim expansion, a strongly religious war.
Muslims and Christians have been fighting over the Balkans and Eastern Europe for hundreds of years. Ottomans go forward, they go back ,they go forward.
Face it, since man could think he has been justifying killing other people because their sky fairies aren't his sky fairies. The justification for going and taking your neighbours stuff is not that it you want it, it's that you want it and he isn't of your (religious) tribe.