Caution: both my reporting of facts as known to me and whatever opinion is inevitably conveyed by my phrasing, this is all subject to commentary regarding the Islamic part from Tamerlane, Aldebaran, or other Muslim in/from areas which have been Islamic for centuries, as well as the same from any person of Jewish descent WRT conversion from Judaism who has the historical knowledge. Most people who are from Islamic lands, as well as we who are interested and have learned about it, have strong opinions about it. I am trying to be careful not to offend the rules for the GQ forum so that this thread will not need to be moved to GD.
Just as a person who is born into a Jewish family with strong religious or cultural identity, Muslims do not recognize or accept that someone once born or converted to Islam as having the ability to change their identity.
Strictly observant religious Jews have, through much of the time since the high Middle Ages, regarded family members who converted to either Islam or Christianity as having died, and behave as if they had, including holding appropriate mourning ceremonies (“sit kiddush/kaddish[COLOR=DarkOliveGreen](sp? and I get confused about the meanings)”)[/COLOR].
The following should not be construed as a condemnation of any individual Muslim, nor is it intended to be derogatory WRT Islam, even though I am mostly not an admirer of it. I have known many Muslims, both when I was in college and in other contexts. All whom I have met have been very friendly people who were enjoyable to know and to spend time with.
In Islamic lands, even those which have national laws guaranteeing freedom of religion (as Islamic law - shariat - does, to a limited degree, for those who are born & raised in another monotheistic religion with written scriptures, AKA “People of the Book,” which predates Islam throughout its history, so long as they pay a tax) it has often been observed more in the breach than not.
Someone raised Muslim does not have the freedom to convert, and this is written into the laws of more than one Islamic state. If the family learns of it, the family will put heavy pressure on them to recant, same with the government. I know of several siblings from a Lebanese Muslim family who immigrated to the U.S., and converted to Christianity after arriving here. The one sibling I know is one of my sources for this information. I also know an Egyptian man who came to the U.S. to go to college and who converted before finishing college. He was disowned by his family, and has been unable to return home even to visit because of the pressures. I should add that the family pressure is augmented by similar pressure from others who learn of it. I have also heard/read reports of this. Please note that this doesn’t only apply to conversion to Christianity. I knew an Iranian grad student who had become a convinced atheist. He also was afraid to go home because of the intense pressure he would receive to return to practicing Islam.
IOW, think of the sort of intense familial/community pressure that an individual raised in a very intensely practicing conservative-wing Baptist (yes, there are many different variations on intensity and severity among Baptist organizations), or an equally intense Pentecostal or Catholic family. The lectures, harangues, tears, partial shunning, and many of the other ways that social pressures are brought in any “closed” community. And in those nations which have non-conversion laws, it may be the family’s duty to report the individual’s conversion.
Given this circumstance, I’m sure you can understand why excommunicating a Muslim is simply unimaginable.