The Muslim American Society has a bio on him with an approving tone, but which does not mention religion
According to discoverthenetwork.org:
Barack Obama was born in 1961 in Hawaii to a white mother from Kansas and black father from Kenya who met while attending the University of Hawaii. His mother Anna, as Obama describes her in his 1995 memoir Dreams from My Father: A Story of Race and Inheritance, was "a lonely witness for secular humanism, a soldier for New Deal, Peace Corps, position-paper liberalism."So we have a father and stepfather who are "non-practicing Muslims", and a "secualr-humanist" mom who seems to have a thing for "non-practicing" Muslims, as evidenced by her repeated marriage choicesHis father, also named Barack (Swahili for "One who is blessed by God," and perhaps via Arabic and Semitic roots related to the Hebrew baruch, "blessed") Obama, left his rural Luo-speaking village and his Muslim father to become an "agnostic" and study economics abroad. His son was two when the elder Barack left the boy and his mother to return to Harvard University and then to Kenya, where he became a globe-traveling economist for the government.
When young Obama was six, his mother married an Indonesian oil manager, a "non-practicing Muslim," and the family moved to Jakarta, where his half-sister Maya was born. In this exotic Islamic country, wrote Obama's good friend, the liberal lawyer and best-selling novelist Scott Turow, Barack Obama spent "two years in a Muslim school, then two more in a Catholic school."
I don't think it's a productive issue, but I believe the Luo, his dad, are largely animists.