Obama's lack of experience on the national stage became a recurring theme used by his rivals Hillary Clinton and John McCain during the presidential election season of 2008. Obama's perceived combination of political savvy, calm temperament, and some conservative support have all been credited with his election to the presidency.

Obama is regarded and self identifies as African-American, although he is of a biracial background. His father was a black Kenyan from the Luo ethnic group and his mother was white of European descent, mainly of English lineage. Obama, who grew to adulthood after the Civil Rights movement, had early life experiences that differed from many African American politicians who launched their careers in the 1960s through participation in that movement. He was brought up in Honolulu, Hawaii, lived in Jakarta, Indonesia as a young child, and received a private prep school and Ivy League education.

In a March 2007 op-ed, African-American film critic David Ehrenstein of the L.A. Times said that Obama was an early popular contender for the presidency not because of his political record, but because whites viewed him as a kind of "comic-book superhero", a benign magical Negro who would selflessly solve white people's problems. Black commentators such as Stanley Crouch of the New York Daily News expressed mixed feelings about his racial identity, while others like Laura Washington (Chicago Sun-Times), Gary Younge (The Nation), and Clarence Page (Houston Chronicle) reported a general ambivalence among the black community about his authenticity as an African-American.

In January 2007, The End of Blackness author Debra Dickerson warned against drawing favorable cultural implications from Obama's political rise: "Lumping us all together," Dickerson claimed it, "erases the significance of slavery and continuing racism while giving the appearance of progress." On the liberal website Salon Debra wrote, "African-American, in our political and social vocabulary, means those descended from West African slaves, because Obama is not a descendant of West Africans brought involuntarily to the United States as slaves, he is not African-American" Stanley Crouch wrote in a New York Daily News "Obama's mother is of white U.S. stock. His father is a black Kenyan," in a column entitled "What Obama Isn't: Black Like Me."

Addressing the issue of whether he was "black enough," Obama told an August 2007 meeting of the National Association of Black Journalists that the debate was not about his physical appearance or his record on issues of concern to black voters. Obama said, "we're still locked in this notion that if you appeal to white folks then there must be something wrong."

After a McCain advertisement accused Obama of being just a celebrity like Britney Spears or Paris Hilton, Obama asserted that McCain and other Republicans would try to scare voters because he (Obama) "doesn't look like all those other presidents on the dollar bills." A subsequent poll by Rasmussen Reports found that although only 22% of Americans (58% of African-Americans) viewed McCain's advertisement as racist, 53% saw Obama's response as such (44% of African-Americans). The Obama camp initially denied that the comment was on race, but campaign strategist David Axelrod later conceded that it was.

Though the media discussed his racial and ethnic heritage, a 2008 post-election poll by FactCheck.org found that about 22% of Americans incorrectly believed that Obama is nearly half Arab, possibly due to the influence of misleading blogs and e-mail messages.

In The Audacity of Hope, Obama writes that he "was not raised in a religious household". He describes his mother, raised by non-religious parents (whom Obama has specified elsewhere as "non-practicing Methodists and Baptists") to be detached from religion, yet "in many ways the most spiritually awakened person that I have ever known". He describes his father as "raised a Muslim", but a "confirmed atheist" by the time his parents met, and his stepfather as "a man who saw religion as not particularly useful". His spiritual change of heart as an adult and his coming to believe in Christianity is a major part of his autobiography Dreams from My Father. Obama has stated that he "felt a beckoning of the spirit" at this time. He has also said that his political/ethical beliefs are "guided by his Christian faith" including belief "in the power of prayer."

Although Obama is a Christian, some July 2008 polls showed that some Americans incorrectly believed that he is Muslim or was raised Muslim (12% and 26%, respectively, in Pew and Newsweek polls). Citing the latter poll by CNN's Larry King, Obama responded, "...I wasn't raised in a Muslim home," and he said that advancement of the misconception insulted Muslim Americans. In November 2008, James Zogby, president of the Arab American Institute expressed in a news report (reacting in part to a satirical New Yorker cover) that ethnic caricature involving faulty depiction of Obama's faith harms Muslim Americans, impeding their "opportunity to participate in the political process."

Much of the speculations and allegations came from chain e-mails of unknown origin during Obama's presidential campaign. A publication which speculates about Obama's concealed Muslim religious affiliation include The Obama Nation (published August 1, 2008) by Jerome Corsi. His book opens with a quote by Andy Martin, who The Nation, The Washington Post, and The New York Times have identified as the primary source for the allegations that Obama is concealing a Muslim faith. Middle East scholar Daniel Pipes has also repeatedly claimed that Obama is a Muslim.