A 1,400-year-old theological dispute over the Nicene Creed threatens to reopen the controversy in the Episcopal Church over revisions of the Book of Common Prayer, which the church's General Convention agreed on last September.

The dispute centers around what has come to be known as the "filioque" clause -- the assertion in the creed that the Holy Spirit comes from Christ as well as from God.

At issue is the inclusion of the last three words of the section of the Creed: "We believe in the Holy Spirit, the Lord and giver of life, who proceeds from the Father and the Son."

Inserted more than two centuries after the creed was agreed on in 381, the filioque -- Latin for "from the Son" -- clause was a major factor in the 11th century schism between Rome and the Eastern Churches. Orthodox churches today still vehemently reject the phrase. Historians and theologians agree it was not part of the formulation handed down by the Council of Nicea in 381, but because of tradition, it continues to be used in western churches.

Now, an unofficial but influential group in the Episcopal Church, the Associated Parishes, has asked that the phrase be deleted from the new prayer book to remove "a cause of scandal and offense to all Christians of the Eastern churches, and a source of embarrassment to some in our own church."

The Episcopal House of Bishops has agreed to take up the request when it meets in October.

Even if the bishops agree that the change should be made, it will be 1985 before the modification can work it way through the machinery of the church. The church's constitution requires that changes in the liturgy, which is involved here, require approval by two of the church's triennial General Conventions.

The process of revising and updating the Book of Common Prayer was completed at last September's Convention after more than a decade of tumult that saw a number of parishes and individuals withdraw from the denomination in protest.

The Rev. Henry Breul of St. Thomas Episcopal Church here, a leader of Associated Parishes, doubted that a reconsideration by the church of the filloque clause might reopen debate on other aspects of the prayer book revision controversy.

"I don't think it would cause any trouble," he said. "Everybody knows it (the phrase) shouldn't be there in the first place. It's a medieval mistake."

Although revisers of the prayer book had eliminated the phrase, he said, the House of Deputies in the General Conference four years ago put it back in. The previous revision of the prayer book, the 1928 revision, included the phrase, as does most Roman Catholic liturgy. Breul said.

Orthodox-Episcopal relations were shaken by the latter's decision four years ago to ordain women to the priesthood. The deletion of the offending phrase in the Nicene Creed is seen as an effort to remove further obstacles between the two denominations.