For Christians by the tens of thousands yesterday, the annual celebration of the most important day in their faith-Easter-began at daybreak.

In parks and church-yards, on mountain tops, beside historic national sites, they gathered in the early morning light to commemorate and to rejoice in Christ's resurrection from the dead.

"We don't need to understand it theologically or spell it out in dogma," the Rev. Dr. James David Ford told the crowd gathered on the wet grass of the traffic circle in front of Mt. Vernon. "We just need to proclaim Christ is risen."

Ford, who was appointed earlier this year as chaplain of the House of Representatives, said that in rising from the dead, "Jesus has conquered the last evil . . . he has conquered death." Easter, he said, "is good news instead of bad; it is victory instead of defeat."

Easter sunrise services appear to be increasing in number and popularity in this area. From Sugarloaf Mountain to Fort Washington Park yesterday, from Bull Run Battlefield to Walter Reed Army Hospital's garden, Christians gathered in the early light to celebrate and retell the story of Christ's resurrection.

"We came here this morning because it's Easter and we'd be in church if we were back home," said Inez Bridge of Shelby, N.C., as she and 30 other members of her tour group waited after the service for their bus.

The sunrise service, a project of the Mt. Vernon Rotary Club, had not been on the original itinirary of theri four-day tour here. "We were visiting Mt. Vernon yesterday and heard about it so we arranged to come," she said. "It was just wonderful."

Because the resurrection, which Easter celebrates, lies at the heart of Christian belief, it is a day when believers traditionally flock to churches as well a sto the special sunrise services.

It is a day steeped in tradition, and for some area residents this means worshipping in a language other than English: in Polish for members of the Polish National Catholic Church who gathered in Washington Cathedral's Bethlehem Chapel; in French at a service conducted by the Apostolic Delegate, Archbishop Jean Jadot, in a special service at the Howard University Chapel; in Mandarin at the Berwyn Baptist Church in College Park, where a Chinese Baptist mission church was launched yesterday.

Greek and other Eastern Orthodox Churches, which follow the Gregorian calendar, celebrated Palm Sunday yesterday and will mark Easter next Sunday.

Because Easter is a joyous celebration, many churches yesterday added special choirs of bells, trumpets and tympani to augment and embellish the hymns. The Episcopal Church of Ascenscion and St. Agnes presented the mass in the musical setting of Franz Josef Haydn, complete with orchestra.

Elsewhere, choirs of every denomination, size and degree of musical skill climaxed the morning service with soaring Allelujah Chorus from Handel's Messiah.

As Chaplain Ford put it at the sunrise service, "Christians this morning are up and ready to fight the aches and pains and frustrations and sounding a note of triumph" on Easter. "In a world of change and turmoil, we focus today on a faith that does not change. What else can you say that about? Nothing." CAPTION: Picture, House of Representatives Chaplain Dr. James D. Ford gives sermon at sunrise service at Mt. Vernon traffic circle. By John McDonnell. The Washington Post