It's all so very Darwinian. 
 
Or Christianity, whose one deity/son/whatever spoke of love and compassion, has a colorful history as well, with plenty of cruelty, torture, oppression, and murder, all in the name of its benevolent and loving god. Sometimes it was even to 
protect the name of the all-powerful god, presumably because this omnipotent being needs his little human followers to beat up anyone who bullies him.
But, as some cultures improve themselves despite the local religions, some of the religions evolve to better survive the changing environment. In some cases, this evolution leads to a more tolerant, friendlier persona. In others, the religion develops more powerful weaponry, with the intention of resisting or reversing cultural change that may endanger it.
And many religions don't survive. The list of dead religions is far longer than the list of those still present. It'd be funny if one of the long-dead religions was actually the correct one.
