Maryland Gov. Martin O'Malley's Catholic faith is an important part of his public service, but he does not let it dictate the decisions he makes, he said after celebrating Mass with the pope at Nationals Park in Washington Thursday.

"I would hope that those of us that serve in public office, regardless of our particular religious faith, are informed by that faith and by those ideals and by those beliefs," he said.

A graduate of Gonzaga College High School and Catholic University, O'Malley is viewed as a fairly liberal Democrat. He remains a supporter of abortion rights and stem cell research, which received about $20 million in state funding for fiscal year 2009. The Catholic Church opposes both.

O'Malley was in line with the church's position against the death penalty when he testified against Maryland's use of capital punishment before the House Judiciary Committee in 2007.

Despite any differences between the governor and the teachings of the Catholic Church, O'Malley said Pope Benedict XVI's message of peace and unity was one that could be embraced by people of all political backgrounds.

"I thought that the pope's message today was a message of understanding and strong truth that resonated with the entire crowd regardless of where people might fall with regard to the political spectrum," O'Malley said.

The governor and his father-in-law, former Maryland Attorney General J. Joseph Curran Jr., were among 46,000 who attended the pope's service. O'Malley was among many who received communion.

In 2004, Democratic presidential candidate and Sen. John Kerry of Massachusetts, a Catholic, faced questions about whether he should be denied communion because of his support for abortion rights.

Communion is one of the most important sacraments for Catholics, but many, including church officials, said Kerry's support for abortion rights went against the teachings of the church.

Pope Benedict XVI's appearance at the new stadium marks his first visit to the United States as the Catholic Church's highest leader.

The appearance in Washington is part of the pope's "Christ Our Hope" tour, and the themes of hope, peace and unity were prominent during his liturgy in the capital.