Promoting any religion but Islam (and the specific sect of Islam held by a countries rulers) in about thirty Muslim countries is a capital crime.

Apostasy is punishable by immediate death.

Needless to say this is similar to the Western view only a few generations ago, however the Quran is very specific about it.

I once worked with an American in Saudi who was of Pakistani descent. His father had come to America, converted and Charles Khan was born Christian and American - when this was discovered in Saudi, our employer had a series of meeting with the religious police and officials all the way up to the Governor of the Eastern region. The purpose of the meetings was to determine if he was apostate and whether he needed to be killed.

Fortunately, the relgious scholars pointed to a Fatwa from several centuries ago that, Spaniards of Arab descent who were now Catholic couldn't be killed if they were born outside of Islam. However he was fired and deported in chains.