While some critics have questioned the depth of Obama's religious convictions and his identity as a Christian, DuBois said the skepticism never appeared to unsettle the president's spirituality behind the scenes.
"People are going to believe any range of things about any leader of the country," DuBois said.
Obama has been dogged by conspiracy theorists who invoke his upbringing in Southeast Asia to claim he's a closet Muslim. Other critics have exploited his ties to controversial former pastor Rev. Jeremiah Wright to suggest he harbors anti-American sentiment.
"All the president can do is live out his Christian walk every single day," DuBois said. "The detractors will do their detracting, but at the end of the day it's about his relationship with God and that relationship, from all that I can tell, is strong."
One sign of that faith, according to DuBois, as Obama's establishment of a new White House tradition of a prayer breakfast to mark the Easter holiday.
"The White House had marked other religious holidays for diverse communities before, but never a day specifically focused on the Resurrection, on what the story of Jesus, the death and resurrection of Jesus, meant for the president and for the world," he said. This year's prayer breakfast will be held Friday.
Later this year, DuBois plans publish a book for leaders based on the devotionals he shared with Obama; it will be called "The President's Devotionals."
This fall, he will also begin teaching a course on multi-faith leadership at New York University and launch a new consulting firm, "Values Partnerships," to help state and local governments partner with faith-based groups to tackle social challenges.
"We think that there are great synergies between the private sector and the faith and non-profit community and we're going to help pull those together for both public good and private impact," he said.