The penalty for leaving Islam, also known as apostasy, is death!
Apostasy: Abandonment of ones religious faith.
In Judaism the greatest punishment for abandoning the faith to either follow an atheistic life or another belief system is that your mother and father may disown you.
In Islam, as attested to in the first 3 minutes of this video by an Egyptian cleric, the punishment for rejecting the religion is the loss of your life!
Apostasy or freedom of religion in Islam has a very high price tag!
H/T Creeping Sharia