Humans have endured centuries of hatred and bloodshed in the name of 'peaceful' teachings from all sort of religious leaders, Christ included.
When one group of people believe they are better than another group of people because they follow the 'divine word' of their religious idol, these same believers in peace and love will willingly oppress, discriminate against and even kill those that seek to deny or diminish that word. The divine word is often unchangeable and immutable (ie. from 'god'), so when two groups with unchanging ideals for the world and different belief structures, respects, morals or customs bump up against each other the end result is always bad.
Evolutionarily speaking these people naturally seek the protection that is offered to them within the group belief structure, and choose to become one of the 'herd' because the herd offers them protection from people that are different and might upset that comfort that is offered by the herd. It is the loss of that comfort that they are most fearful of, and this is something the true believer will do anything to protect. Islam professes to be a religion of peace and love, but it's followers kill and maim christians, jews, hindus etc. in the name of islam. Christianity professes to be about peace and love, but its followers actively seek to deny others equal rights (prop 8), or to force others to follow their beliefs (evolution vs creationism, abortion rights, or in the past - racial rights). The same examples of 'out group hostility' are to be found for all religions and the underlying cause is always the same.
In the modern world, which seeks to be guided by reason instead of doctrine, and by science instead of superstition - all religion, no matter how noble and peaceful each professes to be, ultimately causes only harm in the long term.