In America, we have freedom of religion, so the element of personal choice is crucial to the definition of who is and is not a Muslim.
The Islamic definition of a Muslim is, "a person who is born of a Muslim father." In Islam, there is no freedom of religion. A person who is a Muslim who chooses not to be a Muslim anymore is deemed an apostate and is subject to death.
Barack Obama was born of a Muslim father. Therefore, according to Islam, he is a Muslim. According to American values, he is what he says he is; a Christian.
From Robert Spencer at Jihad Watch:
Related: Malik Obama: My Brother Will Be Good for the Jews, Despite His Muslim Background
Barack Obama's new Fight the Smears website says flatly: "Senator Obama has never been a Muslim, was not raised a Muslim, and is a committed Christian."
This, of course, is nothing new: it is just what his campaign has been saying for quite some time. And that's why the mounting evidence that he was indeed known as a Muslim in his youth in Indonesia matters -- not because of some paranoid fantasy that Obama is a Manchurian candidate, a secret Muslim who will tell Americans on January 20, 2009, "Surprise! I'm imposing Sharia!" (I have never credited any of that nonsense) -- but because it raises questions about his honesty.
If he was registered as a Muslim in school and wEnt to Qur'an class (which he refers to doing in one of his books), why not admit that he was at least nominally a Muslim as a child? His conversion to Christianity, and his now-notorious church, are well known. Perhaps he has calculated that admitting this would cost him more in political capital than he is able or willing to pay, but -- so does, or so should, his lack of honesty about this matter.
Daniel Pipes has gathered together the evidence for this as it stands now. Here is some of it:
The Catholic school: Nedra Pickler of the Associated Press reports that "documents showed he enrolled as a Muslim" while at a Catholic school during first through third grades. Kim Barker of the Chicago Tribune confirms that Obama was "listed as a Muslim on the registration form for the Catholic school."
A blogger who goes by "An American Expat in Southeast Asia" found that "Barack Hussein Obama was registered under the name ‘Barry Soetoro' serial number 203
and entered the Franciscan Asisi Primary School on 1 January 1968 and sat in class 1B. … Barry's religion was listed as Islam."
The public school: Paul Watson of the Los Angeles Times learned from Indonesians familiar with Obama when he lived in Jakarta that he "was registered by his family as a Muslim at both schools he attended." Haroon Siddiqui of the Toronto Star visited the Jakarta public school Obama attended and found that "Three of his teachers have said he was enrolled as a Muslim." Although Siddiqui cautions that "With the school records missing, eaten by bugs, one has to rely on people's shifting memories," he cites only one retired teacher, Tine Hahiyari, retracting her earlier certainty about Obama's being registered as a Muslim.
Koran class: In his autobiography, Dreams of My Father, Obama relates how he got into trouble for making faces during Koranic studies, thereby revealing he was a Muslim, for Indonesian students in his day attended religious classes according to their faith. Indeed, Obama still retains knowledge from that class: Nicholas D. Kristof of the New York Times, reports that Obama "recalled the opening lines of the Arabic call to prayer, reciting them [to Kristof] with a first-rate accent."
Pipes has more, with links, at his site.
Melanie Phillips has been looking into all this as well, and she succinctly explains its importance:
As I have already said -- but let me repeat very slowly for those suffering from Princess Obama Derangement Syndrome – the concerns about Obama’s Muslim antecedents arise from the fact that a) he has tried to conceal them and b) that he has a puzzling number of indirect connections with radical Islamists or their supporters.
1) He has gone out of his way to support in Kenya Raila Odinga, head of the Luo tribe, who promised to introduce sharia law if elected. Obama interrupted his New Hampshire campaign to speak by phone with Odinga. As the Investor’s Business Daily has reported, his half-brother Abongo ‘Roy’ Obama is a Luo activist in Kenya and a militant Muslim who argues that the black man must ‘liberate himself from the poisoning influences of European culture’ and urges Barack to embrace his African Muslim heritage.
Phillips has mucg more on this; note also that Pamela has been doing yeoman work on investigating Obama's Kenyan connections, and has a great deal of information.
Again: if Obama had simply acknowledged that he was known as a Muslim as a child in Indonesia, and had left Islam later, none of this (besides the ties to the Islamic supremacists in Kenya) would be of any concern. But he has made it a matter of concern by denying what has been affirmed by so many others.