I've recently done a project on the Islamic Golden Age. Now Islam is one of my favourite religions.
Converting to ISLAAM is one of the best feelings in the world, maybe second only to winning a 40 player FFA. Do it !
People spread religions by war and crusades and then call them peaceful?
All dogmas. Including militant atheism - folk should just not care so much, that is the answer. Where d'you see Christians or Jews in firstworld countries attacking others for faith, other than an occasional exception amongst millions?
Islam itself is divided into two. Shia and Sunni, who dislike each other. Then you have the Saudi interpretation and the Egyptian interpretation.
More than those 2 fiqh and sharia.
http://i.imgur.com/6YEh9.png (and this map is not even including factors outside of fiqh, such as reform movements like Salafism/Wahabbism).
The culture in which they come from is a different story.
Indeed, a shame that some uncivilised tribal Arabian tribal faiths mixed with Judaism and their culture prospered so well and affected other cultures in another way. In Christianity, this is different - noone really believes that old Hebrew and Greek is the special tongue, or that you are not reading the "true" Holy Writ if you don't read the Greek Book. Folk mostly went their own way.
Muslims from a long tradition of secularism (Middle Asia, Azerbaijan, Russia, Turkey) are not the problem, at any rate - they are more conservative than Christians in the lands, but that's nothing.