The problem with Islam...
is that people actually believe it. This isn't really a problem today with Christianity, considering it's more of a cultural tradition than an actual religion. Most socalled Christians today say they believe, but don't actually follow the teachings of the religion. Sex before marriage is perfectly ok, going out partying on Saturday night and being in church on Sunday is the norm as well. Church is more of a social function than an actual act of worship.
The Christian West has been secularized for a long time, now Islam needs a good dose of disbelief for it to become civilized.