John 16:2 They shall put you out of the synagogues:
yea, the time cometh, that whosoever killeth you will think that he doeth God service
This scripture is no myth. Millions of people have died at the hands of people who truely believed they were christians and had God on their side....people who truely believed that 'they' were the ones with the 'only' truth.
But that is an extreme example...and not even what I was really trying to address here.