ummmm, Cultural Jihad, maybe Muslims are so devoted because their holy books tell them it is DEATH to leave Islam. And the way it plays out in the Middle East, often members of their family receive torture if a family member leaves.
No Muslim can deny that to leave Islam, to stop being Muslim, is punishable by death in Islam. On that there are no contradictions.
You would have to ask Muslims in America and Europe, where no civil authority can put them to death for apostacy, why they continue to worship the one same God as the Christians do.