The Rev. Dr. Charles A. Trentham's study is appointed with presidential memorabilia. Harry Truman's church pew is off to one side. George Washington's and Dwight D. Eisenhower's inaugural prayers are framed behind glass. Color portraits of all chief executives cover one wall. And on the coffee table is a copy of Jimmy Carter's autobiography, "Why Not the Best."

Tretham, senior minister of First Baptist Church at 16th and O Streets NW, has never been a president's pastor. But his new role as minister to President Jimmy Carter and his family becomes him.

While the thought of being the President's pastor would have scared some clerics, Trentham was ready. He is a person who does his best in a demanding situation, according to associates.

"When all odds are on him," said one acquaintance "Charlie Trentham can deliver better than anyone."

The softspoken Trentham, a man with white wavy hair, eyes that crinkle at the corners and an easy smile, is a genial Southerner, dapper, grcious and self-assured. He is deliber ate but not aggressive.

"He is a very warm person, some one you automatically have a great deal of affection for the first time you meet," said Dr. William McBeath, Executive director of the American Public Health Association and a First Baptist member for three years.

"He is not someone you stand in awe of but one of the most warmhearted people you'll find," said Alvin West, a Washington lawyer and a First Baptist member since the early 1940s.

Trentham is outwardly attuned to others' feelings and in turn sensitive about what others think of him.

"As he was leaving church on Sunday, the President said to me, 'I want you to know I already feel close to you,'" Trentham recalled. "I was deeply touched. I was feeling the same way. He put me at ease."

Trentham's forte is widely recognized to be his preaching, a tradition among First Baptist pastors.

"The pulpit is my craft," said Trentham. "I am more comfortable in preaching than in any work of the ministry."

Yet, he said, "It is also very hard for me. I'm slow of speech. I have the mountain pattern of East Tennesse."

Trentham's progressive views come through in his sermons the locus of his social action.He leads his people primarily through his words and intellect and by lending his prestige to various projects aimed at bettering society. He is not afraid to speak his mind.

In the pulpit. Trentham turns expressive. He rocks forward on his tiptoes, then back on his heels. His voice rises and falls. His hands grip the lectern. He quotes poetry, famous figures and data from a variety of disciplines frequently without referring to a note.

"He believes in the church's need to attend to social issues," according to Floyd Craig, a staff member of the Southern Baptist Christian Life Commission. Trentham was a member of the commission, the church's social action arm, for six years and chairman for part of the time.

"There are those who would like to see him engage in social action himself, but it is his style to do it from the pulpit," Craig added.

West remembers in the 1960s when he and Trentham were serving on the Southern Baptist Convention's executive committee and racial violence broke out in Birmingham.

"He proposed a resolution deploring the incident and expressing sympathy for the family," said West, now a deacon at First Baptist. "Some committee members took this as a personal accusation against some whites in Birmingham. The resolution didn't pass."

President Kennedy appointed Trentham to an 18-member committee to investigate racial turmoil in Birmingham. "I was a great admirer of Kennedy," the pastor noted.

Charles Trentham was born in Jefferson City in east Tennesse. He earned a doctorate of theology from Southwestern Baptist Theological Seminary and doctorate in moral philosophy at the University of Edinburgh.

He has been a pastor in Fort Worth, Tex., a professor of religion at Baylor University and a professor of systematic theology at Southwestern Baptist Seminary. For 21 years before coming here in 1974 he was pastor of First Baptist Church in Knoxville, Tenn., and dean of the School of Religion at the University of Tennessee.

Trentham, an acknowledged scholar, has written four books - "Shepherd of the Stars," which he calls a "theology of puter space"; "Getting on Top of Your Troubles," a counseling book; "Daring Discipleship," which is given to new church members and a commentary on the Book of Hebrews.

President Carter took a copy of "Daring Discipleship" back to the white House after Sunday's service for Amy, 9, to study. She will be baptized at First Baptist.

Trentham and his wife, Nancy, live in Vienna.

The Carters are not the first First Family to worship at the stately First Baptist Church. President Truman frequently walked the six blocks up 16th Street from thw White House to attend services there.

Undoubtedly, however, the First Family's presence will have an impact on the 950-member congregation, a predominantly middle-aged and older group of many leading Baptists in town.

Trentham and his associate pastor, the Rev. Charles Sanks Jr., are elated at the prospects.

"We are greatly concerned that we use what we believe is out ime well, that we do something positive for the nation through this," Trentham said.