Shortly after the Civil War, a group of Northern Virginians, most of them former slaves, put together the money they had saved for years to buy mortar and timber to build the Mount Pleasant Church near Herndon.

The small, white-frame church with its steeple and bell tower was set in the countryside, amid rolling hills and fields of golden corn and only a short distance from a pond used for baptisms.

Last week, 115 years later, descendants of the founding members left the old church for a new cinder-block and brick building built with nearly two decades' worth of savings by the members.

"It is just history repeating itself, tradition going on and on," said Diane Nokes, whose great-grandmother is buried in the well-kept graveyard behind the old church. "My Granddaddy used to say they saved walnuts and sold them to buy mortar for the old church. We are a poor family church. We prayed and saved almost 20 years to build this new church."

Last Sunday, Nokes and church members gathered in front of the old building for a symbolic walk across a rutted country lane to the new church.

The Rev. Lloyd O. Roberts led the congregation of 300, fortified by friends and visiting clergy. The members and guests were in their Sunday best: flowered dresses and hats, three-piece suits and old-fashioned hand fans provided by a local funeral parlor.

As the group moved to their new building, the choir sang an old hymn:

"This old building, keeps on leaning.

"I've got to move, to a better home."

Roberts turned to his congregation.

"The Lord is good, isn't He?" he asked.

"Amen," came the answer.

Most church members credit Roberts with turning their dream church into reality. Roberts credits God. "He has provided an answer to our prayers," Roberts said. "It is a symbol of our faith and desire."

When Roberts became pastor in 1978, he said, members already had saved $18,000 for the new building, far short of the money needed. "We were about to lose our building permit," he said. "I asked each family to pray and give $1,000. From that we raised $39,000."

A local contractor built the new church for $200,000. To supplement members' contributions, the congregation borrowed $100,000 from a bank and the contractor to finance the church. About $87,000 remains to be paid on the loans.

But the congregation contributed more than money. After major construction work had been done, members painted the hall and hung the 10 new glass chandeliers.

Members of the Best family, which traces its roots to the founders of the church, painstakingly crafted two blue-and-gold stained-glass windows that they donated for the new building. The worn wooden pews and altar from the old church were moved to the new building.

"This is the answer to a long prayer," said Deacon Lester Best of Herndon as he walked in step to the gospel music. "It is what we dreamed for."

Most family members at Mount Pleasant are related, Nokes said, and come from Virginia, Maryland and the District to attend the church on Coppermine Road in Herndon. The Bush, Best and White families, all descended from church founders, are prominent among members of the congregation.

Mount Pleasant is said to be the first black Baptist church in Virginia. After the Civil War, one Charles H. Brown sold 60 acres of farmland to black freedmen, as freed slaves were called. Brown later deeded one acre to the "freedmen of Fairfax County . . . to be used exclusively for religious and school purposes and a burying ground."

Because the church was on a hill and the congregation was known to be cooperative and friendly, it acquired the name Mount Pleasant. For years the original church building doubled as a one-room schoolhouse for blacks.

"It is a shame to leave this building; there is history here," said Nokes as she walked into the musty, now-empty church.

There is talk of turning the building over to an historical society for preservation. But Roberts said that if no one is interested in preserving the building it will be torn down for a parking lot. The graveyard will remain.

Members said that although they will miss the old building, the new church is long overdue. In back of the original church, in the graveyard, two ancient outhouses lean precariously. The old building has no plumbing.

Although the new church is made of brick and the old of pine timber, the buildings resemble each other: small with long pointed windows and a bell tower on one side.

"The church was made small to accommodate the faithful few," said Nokes' cousin, Adrienne Chichester, who held her 5-month-old son, Aaron. "We are a close church, very dedicated."

She pointed out the grave of her grandmother, Katherine Bush. She had 17 children, Chichester said, but most died in an epidemic.

"They are buried back here somewhere," she said. "We go way back. This new church is a part of very old families. We are related by blood as well as being children of God. This church is very special to us. That's why we worked long and hard for it."