To leave the Islamic faith or to attempt to convert others away from the faith warrants capital punishment under Sharia Law.
Not everyone who says he or she is a Muslim believes that; but so long as the Supreme Leader in Iran, Ali Khamenei, does, it's a major problem. I have written openly that if he murders (yes, it would be murder) Youcef Nadarkhani, I would no longer speak out for Iran against the Zionist lies about Iran's non-existent nuclear-weapons program.
Look, there are plenty of things about Islam with which I don't agree, but Mohammed himself wrote (said) in the Qur'an that there is no compulsion in religion. How can Iran execute Youcef Nadarkhani if they believe that statement that there is no compulsion in religion?
Yes, it would be horrendous were the Likudniks to attack Iran and also murder innocent people, people who are not building toward nuclear weapons. However, it is up to the Iranian people to decide whether it is right to murder someone who uses his God-given freewill to decide between Islam and Christianity and chooses Christianity. If the Iranians can't rise up to institute such freedom of conscience in religion, then that will be their problem with God, and Satan will have his way with them.
Not only that but they are not to simply leave him to rot in jail. Let him out!