Well, Islam did have their own Golden Age, and it came way, way earlier than Christianity's, so that bit about being a bit of a mess because it's a younger religion is kind of baseless.
Geopolitics had a lot to do. Having a rather polarizing figure presiding the largest church in the world (ie: the Pope) also played a huge part in eroding Christianity's influence from government and society.
Like I said. They had a strong beginning, but withered after the Mongol Invasion and Crusades which basically put them back to square one. So the 600 years less development time certainly didn't help with their modernisation and they fell far behind Christianity.