Luttwak (author of the how-to manual 'Coup d'etat') points out how the Muslim world will interpret Obama as an apostate Muslim and be out a'gunning for him.
But remember, you read it here first: http://rantsand.blogspot.com/2008/02/why-barack-hussein-obama.html
Of course, as most Americans understand it, Senator Obama is not a Muslim. He chose to become a Christian, and indeed has written convincingly to explain how he arrived at his choice and how important his Christian faith is to him.
His conversion, however, was a crime in Muslim eyes; it is “irtidad” or “ridda,” usually translated from the Arabic as “apostasy,” but with connotations of rebellion and treason. Indeed, it is the worst of all crimes that a Muslim can commit, worse than murder (which the victim’s family may choose to forgive).
Because no government is likely to allow the prosecution of a President Obama — not even those of Iran and Saudi Arabia, the only two countries where Islamic religious courts dominate over secular law — another provision of Muslim law is perhaps more relevant: it prohibits punishment for any Muslim who kills any apostate, and effectively prohibits interference with such a killing.
At the very least, that would complicate the security planning of state visits by President Obama to Muslim countries, because the very act of protecting him would be sinful for Islamic security guards. More broadly, most citizens of the Islamic world would be horrified by the fact of Senator Obama’s conversion to Christianity once it became widely known — as it would, no doubt, should he win the White House. This would compromise the ability of governments in Muslim nations to cooperate with the United States in the fight against terrorism, as well as American efforts to export democracy and human rights abroad.