Well, being contradictory is nothing that ever stopped people (religious or not). For example Jesus was all about piece, yet horrible attrocities have been done in his name by people saying their were for Jesus ideals (e.g. the Spanish Inquisition, the genocide of Latin American indians, etc).
There's documentary evidence, via Wikipedia, to support 1250 being sentenced to death by the Spanish Inquisition over a 200 year period. The monarchy in Spain established that Inquisition: the people were tried for things like witchcraft but also child rape, bestiality and such which are still consider serious crimes today - though seldom is capital punishment legally applied for those crimes now. Interestingly none of the motives mentioned in the Wiki' article is "spreading Christianity": indeed IIRC the Inquisitions apply to those "baptised" in to the Catholic church [albeit baptisms were often under duress of being expelled from Spain it seems].
Whatever atrocities can be pegged on Christians I don't see how that stops the Koran and Mohammed from being supporters of violent persecution however.
Sikhism has violent elements in it's historical fundamentals too, from what I've read. But they have appear to me to have been 'editted' out to some extent (cf history of the kirpan).
Whilst Shintoist Japanese were involved in horrible atrocities Shintoism, at least Confucian Shintoism, historically was quite anti-war.
Simply being an adherent of a particular way or faith or religion and performing violence doesn't make that 'way' a violent one. There is a great difference between this and the foundation and fundamental teachings including violence.