you think Islam came from thin air?
Islam is not inherently worse than Christianity at it's core fundamentals, because they both contain loads of barbaric crap. As recently as a couple hundred years ago, Christianity was much like Islam, even worse in terms of it's violence and dogmatism.
The difference is that the ideas of the Enlightenment have been simmering with Christian philosophers and laymen alike for hundreds of years and having a moderating influence.
Christianity would look identical to today Islam few hundreds years ago.