I have that same uncomfortable suspicion. He was educated, i.e., brainwashed, in Indonesian Muslim schools for several years as a child and that kind of intense indoctrination early in life is hard to overcome later on even if you want to, and nothing says that he wants to. Joining a large Black Liberation theology "Christian" church was a good way to get support for his local and state political career in Chicago.
Now it has come out that the Rev. Wright who he holds in such high regard was once a Muslim. Something terribly fishy here.