A Methodist pastor of a Kansas megachurch who has written popular books on world religions and the importance of accepting doubt will deliver the sermon Tuesday to the Obamas and others at the official inaugural prayer service at the National Cathedral.

The Rev. Adam Hamilton, who pastors the 16,000-member United Methodist Church of the Resurrection, will preach at the morning interfaith prayer service, an inauguration tradition since the 1930s. The services, held the day after the inauguration, have almost always been held at the National Cathedral, the highest vantage point in the city and one of the world’s largest cathedrals.

The service is heavily interfaith and includes prominent guests of the administration and faith leaders. It is planned by the inaugural committee and this year will also include anthems sung by soloist Wintley Phipps and the Washington Performing Arts Society’s Children of the Gospel choir – both of whom sang at President Obama’s last inaugural prayer service. Other musicians will be “The President’s Own” Brass Ensemble of the U.S. Marine Band and the Cathedral Choir.

The service is invitation-only but will be webcast live at www.nationalcathedral.org.

Hamilton heads one of the country’s most visible mainline churches and is often quoted as a faith leader embracing ambiguity — in politics, interfaith matters, relationships and in personal spiritual doubt. His books include “Seeing Gray In A World of Black and White.”

He was in the news last year when his denomination voted to maintain their official stance that gay and lesbian act are “incompatible with Christian teaching.” Hamilton argued for a middle-ground proposal that would have changed the Methodist Book of Discipline to say that gays and lesbians are “people of sacred worth” and would have noted that church members are split on God’s intention about same-sex relations. The measure failed.

There will be two prayers during Obama's actual swearing-in on Monday — first an invocation by Civil Rights activist Myrlie Evers-Williams and then a benediction by the Rev. Luis Leon, an Episcopal priest.