President Obama drew on the Bible and his interpretation of the Christian faith Thursday to deliver a sharp, if tacit, critique of his chief Republican rival’s economic program, speaking at a forum that in the past has been largely free of electoral politics.

Speaking to about 3,000 people at the annual National Prayer Breakfast, Obama emphasized the importance of his Christian beliefs in his politics and personal life, arguing that his efforts to raise taxes on the wealthiest Americans, promote health insurance reform, help families with college tuition and send troops to prevent human rights abuses in Uganda were grounded in his faith.

“I think to myself, if I’m willing to give something up as somebody who’s been extraordinarily blessed, and give up some of the tax breaks that I enjoy, I actually think that’s going to make economic sense,” Obama told the audience. “But for me, as a Christian, it also coincides with Jesus’s teaching that ‘for unto whom much is given, much shall be required.’ ”

Obama’s remarks injected religion, a politically treacherous issue for him and for Republican front-runner Mitt Romney, into the center of the presidential race. His willingness to do so suggested a new confidence in his evolving reelection message that restoring fairness to the American economy is crucial to its long-term success.

A Christian, Obama has faced voter doubts about his religious convictions for years, some of which have grown during his time in office. He is the son of a non-practicing Muslim father and a mother whom he has characterized as spiritual but not formally religious.

Obama has also faced charges from GOP critics that he and his administration are at war with traditional religion.

But on Thursday, he sought to resolutely affirm his relationship with the Christian mainstream, which is terrain that Romney, a Mormon, has had some trouble navigating politically.

A tacit critique of Romney

Obama described his “faith journey” again in terms that coincide with the central themes of his reelection effort, drawing on biblical passages that have helped underpin his belief in what is called “the social gospel.”

Obama spoke a day after Romney, who faces doubts within his party’s evangelical Christian base concerning his Mormon faith, said in an interview that he is “not concerned about the very poor” because they have a social safety net.

Romney’s intent was to emphasize his focus on the struggling American middle class. But, with those remarks in the background, Obama pointedly highlighted families “struggling to find work or make the mortgage, pay for college, or, in some cases, even to buy food.”

“The Bible teaches us to ‘be doers of the word and not merely hearers,’ ” he said. “We’re required to have a living, breathing, active faith in our own lives. And each of us is called on to give something of ourselves for the betterment of others.”

Before his election as president, Obama spoke about the need for Democrats to speak more forcefully about faith rather than cede the issue — and millions of religious voters — to Republicans in every election.

Although the Obamas have not regularly attended church in Washington, Obama noted Thursday that he prays each morning and speaks frequently with ministers and religious advisers at times of stress.

But some conservative leaders reacted with disappointment to Obama’s remarks, saying that the president chose to politicize the event. It was Obama’s third appearance as president at the breakfast — he also attended as a U.S. senator — and his remarks were more explicitly political in nature than those he delivered last year.

Ralph Reed of the Faith and Freedom Coalition, who is also a prominent GOP strategist, said that for Obama to tie his tax policy to Jesus’s teachings “is theologically threadbare and straining credulity.”

“I felt like it was over the line and not the best use of the forum,” Reed said. “It showed insufficient level of respect for what the office of the president has historically brought to that moment.”

Furor over birth control

Obama has come under fire for his decision last month not to exempt most faith-affliated organizations, such as Catholic hospitals and universities, from a provision in the health-care law that will require employers to cover birth control without out-of-pocket costs as part of new insurance plans for workers. (Churches and other institutions of worship are exempt from the rule.)

The decision is emerging as a campaign issue, and some religious conservatives have used the decision to argue that Obama is hostile to the practice of religion.

Catholics in thousands of parishes heard a letter from their bishops last weekend rallying against the rule, and even some prominent liberal Catholics in recent days called the rule a threat to traditional Catholic practice.

Shaun Casey, a Wesley Theological Seminary professor and evangelical adviser to the Obama campaign in 2008, said the White House is misjudging the political fallout among Catholics, who may see the process as disrespectful.

“This decision has drawn negative reaction from an astonishing breadth of sources. The most troubling is the strong response from people who are usually the president’s allies,” Casey said. “For a White House that prides itself on outreach to faith groups, the apparent breakdown in process is puzzling. I am not sure they understand the size of the political problem they are facing.”

Though studies indicate that a large majority of Catholic women have used contraception, some Obama supporters acknowledged that his decision carried political risks.

“This has nothing at all to do with abortion, but . . . if it is framed that way, voters who tune in quickly could have much more blowback” for the White House, said Eric Sapp, a consultant to Democrats on faith issues.

Emerging campaign issue

Some GOP consultants say their party aims to make this a key campaign issue.

Former candidate Rick Perry has been the most bold, releasing a video vowing to end the “war on religion.”

At a campaign rally this week, Newt Gingrich charged that Obama was “declaring war on the Catholic Church.” Romney, citing the health-care law, used similar language, calling it an “assault.”

Some experts said the controversy could harm the president, particularly in battleground states with sizable white Catholic populations, including Ohio, Pennsylvania, Wisconsin and Michigan.

Obama carried 54 percent of Catholic support in his 2008 campaign against John McCain, but that support dropped to 47 percent among white Catholics voters and 41 percent among Catholics who regularly attend Mass.

In his remarks Thursday, Obama did not directly join the debate over religious freedom.

But he laid out a simple scriptural grounding for his policies: caring for the least of these, being one’s brother’s keeper, demanding much of those to whom much has been given. He went on at length about a meeting with evangelical icon Billy Graham.

“I have fallen on my knees with great regularity since that moment, asking God for guidance not just in my personal life and my Christian walk, but in the life of this nation,” he told the crowd at the Washington Hilton.

Staff writers Scott Wilson and Peter Wallsten contributed to this report.