He attended the First Congregational United Church of Christ in Iowa to display his faith not only to God but also to a crowd of media representatives, agitated by an Internet rumor Obama is a Muslim and poses a treat to the country’s security.
He did not refute the rumors directly, but told how he joined Trinity United Church of Christ in Chicago nearly 20 years ago.
"What I found during the course of this work was, one, that ordinary people can do extraordinary things when they come together and find common ground," he told the congregation. "The other thing I discovered was that values of honesty, hard work, empathy, compassion were values that were spoken about in church .... I realized that Scripture and the words of God fit into the values I was raised in."
Obama is known to invoke religious references in his speeches and has said he has a "personal relationship" with Jesus Christ. He often has said that religion has a place in public life and that faith and politics are not exclusively the domain of conservatives.
Obama staffers and volunteers say they periodically encounter voters who say they cannot support Obama because he is Muslim, a claim that has been making its way through Internet sites and blogs since he announced his candidacy. Aides say he regularly attends church on Sundays, even while on the road, but without the news media watching.
Earlier this month, rival Hillary Rodham Clinton's campaign forced the resignation of two Iowa volunteer coordinators who had forwarded e-mails that tried to tie him to Islamic jihadists.
Obama - whose middle name is "Hussein" - was born in Hawaii and moved to Indonesia at age 6 to live with his mother and stepfather, who was Muslim. He left Indonesia when he was 10 and returned to Hawaii to live with his mother's parents.