His is a nonpartisan position, one of just a few in the Senate, and he prefers to leave his political leanings vague. He was chosen in 2003 by Senator Bill Frist, a Tennessee Republican who was the majority leader at the time, from a group of finalists selected by a bipartisan committee. Before that he ministered in the Navy for nearly 30 years.

“I use a biblical perspective to decide my beliefs about various issues,” Mr. Black said in an interview in his office suite on the third floor of the Capitol. “Let’s just say I’m liberal on some and conservative on others. But it’s obvious the Bible condemns some things in a very forceful and overt way, and I would go along with that condemnation.”

Last year, he participated in the Hoodies on the Hill rally to draw attention to the shooting death of Trayvon Martin. In 2007, after objections from groups that did not like the idea of a Senate chaplain appearing alongside political figures, he canceled a speech he was scheduled to give at an evangelical event featuring, among others, Tony Perkins of the conservative Focus on the Family and the columnist and author Ann Coulter.

Mr. Black, who is the first black Senate chaplain as well as its first Seventh-day Adventist, grew up in public housing in Baltimore, an experience he draws on in his sermons and writings, including a 2006 autobiography, “From the Hood to the Hill.”

In his role as chaplain, a position that has existed since 1789, he acts as a sounding board, spiritual adviser and ethical counselor to members of the Senate. When he prays each day, he said, he recites the names of all 100 senators and their spouses, reading them from a laminated index card.