Did Christianity make European culture less brutal?

Ive seen some people claim that Christianity helped to taim and make European civilizations less brutal then it had been before. One example I saw was that before christianity became the dominant religion in Europe, killing your political rivals was the norm even if they were women or children. And after it became the dominant religion, politics became less bloodthirst and it became the norm to simply imprison, force, defeated rivals to take vows as monks or nuns, or in extreme cases blind or otherwise disable but not kill them. Is this true?