Throughout the history of Christianity there have been plenty of clerics and holy figures more than prepared to lift up a sword and slay in the name of Jesus. Take for example Bishop Odo of Bayeux, the half-brother of William the Conqueror who had no difficulty joining the Norman leader when he invaded England in 1066. He enthusiastically joined the army at Hastings and though not permitted to strike or kill with a sword, he resorted to wielding a club with gusto during the battle. So proud was Odo of his exploits on that victorious day that he commemorated it in the Bayeux tapestry, which he commissioned, to ensure his contribution was duly immortalized.
Medieval bishops were major landowners in their own right and could be just as ruthless as any secular ruler in their treatment of the serfs. The downtrodden might decide that their lot was so grim that revolt was the only option. The people of Drenth, who had been handed over to the not so tender mercies of the Bishop of Utrecht by the Holy Roman Emperor, rebelled against their clerical overlord in 1228. Bishop Otto was in no mood to tolerate this impudence and rode out in to battle with an army to put his surly serfs back in their place. Unfortunately for Otto he hadn’t reckoned on the level of hatred he had built up in Drenth and his force was defeated at a village called Ane. The bishop was cut down and killed.
The Catholic Herald lists other examples of tough clerics including, of course, the Knights Templar, the Knights Hospitaller and the Teutonic Knights. But also consider the astonishing sight of Pope Julius II who was spotted by the great Renaissance thinker Erasmus riding back from a military skirmish in full battle armour.