President Barack Obama made a clear declaration of his Christian faith on Thursday and seemed to express some frustration that his beliefs continue to be called into question.

OBAMA/"Let me tell you, these past two years, they have deepened my faith," Obama told a ballroom full of applauding believers at the annual National Prayer Breakfast in Washington.

"The presidency has a funny way of making a person feel the need to pray."

He detailed how, after a non-religious upbringing, he came to define himself as a Christian.

"A call rooted in faith is what led me, just a few years out of college, to sign up as a community organizer for a group of churches on the south side of Chicago," he said.

"And it was through that experience, working with pastors and laypeople, trying to heal the wounds of hurting neighborhoods, that I came to know Jesus Christ for myself and embrace him as my Lord and Savior."