Graham, who with his father Billy Graham prayed with Obama earlier this year, told CNN in an interview broadcast Thursday: "I think the president's problem is that he was born a Muslim, his father was a Muslim. The seed of Islam is passed through the father like the seed of Judaism is passed through the mother. He was born a Muslim, his father gave him an Islamic name."
Graham did not offer any evidence for his belief.
"Now it's obvious that the president has renounced the prophet Mohammed, and he has renounced Islam, and he has accepted Jesus Christ. That's what he says he has done. I cannot say that he hasn't. So I just have to believe that the president is what he has said," Graham told CNN, adding, "The Islamic world sees the president as one of theirs."
Obama has written that his father, Barack Obama Sr., was a confirmed atheist by the time he was born, and had little contact after he divorced his mother when Obama was 2, ABC News reported.
Meanwhile, about one in five Americans, 18 percent, wrongly believes Obama is a Muslim. The non-partisan Pew Forum said that number was up from 11 percent in March 2009.
Americans who correctly believe Obama is a Christian declined from 48 percent to 43 percent, the poll indicated, ABC reported.
The Pew poll was conducted between July 21 and Aug. 5, before Obama's comments on the plan to build an Islamic center near Ground Zero in Manhattan. The report did not give a margin of error.
"The president is, obviously, Christian. He prays every day," a presidential spokesman said.