“Holy War” an oxymoron or not?

I believe that Holy War is an oxymoron. "Holy" meaning specially recognized as or declared sacred by religious use or authority and "War" meaning a conflict carried on by force of arms, as between nations or between parties within a nation. They are opposites in definition and concept, with Holy being something sacred and special, and War being something horrific and violent. Though "Holy wars" have been declared there has never been any war in history which was sacred as such. I believe many wars today, that are declared because of religion, are largely to do with the difference in beliefs and the idea that there God is the only God. The religion may condemn killing, but as the people they are killing are not part of the religion there actions are justified. Often the people who do kill may say they are killing for there religion but truth be told they are killing because of a personal choice and beliefe.