325 A.D. –  First Council of Nicaea: Incorporating long-held baptismal creeds of local churches spread across the Roman Empire, the initial seven articles of what will become the Church’s universal creed or “Symbol of Faith” are formulated at Nicaea. This first universal gathering of Christian hierarchs, those standing in direct succession from Christ’s apostles and as the leaders of the undivided Church, is the first of seven “Ecumenical Councils.” Fully recognized by both the Roman Catholic and Eastern Orthodox Churches, these seven councils convened over time largely to combat the spread of heresies (non-apostolic doctrinal innovations) among local churches and rebellious hierarchs.

At First Nicaea, the teachings of the churchman Arius are specifically declared heretical. (Arianism, the predecessor of the doctrines of modern-day Jehovah’s Witnesses, maintains that Christ was himself a creature, subordinate to the Father and not eternally and ontologically co-existent with him.)

381 A.D. – First Council of Constantinople, the second Ecumenical council: The Creed of 325 A.D. is affirmed and expanded, resulting in the statement we now popularly call the “Nicene Creed.” The official statement of apostolic Christian faith, the Creed of 381 is formally referred to as “The Creed of Nicaea-Constantinople.”

431 A.D. – Council of Ephesus: The Creed of Nicaea-Constantinople is declared complete and not subject to further revision.

447 A.D. – Synod of Toledo: The Filioque clause (that the Holy Spirit proceeds eternally from the Father and the Son) is introduced into the Creed. The Synod of Toledo, a local synod of bishops from a region governed by the Roman Church, mandates the addition in an ill-considered attempt to combat resurgent Arian sympathies in the western regions. Over time, the other apostolic churches in the East come to fiercely protest this unilateral change to the Creed as a clear violation of the conciliar decrees of the entire Church, and find fault with its theological implications and impact on church governance.

1014 A.D. –  Due to the demands of the newly crowned Holy Roman Emperor Henry II, the Creed of Nicaea-Constantinople together with the Filioque clause is used for the first time during a Mass presided over by a Pope. The Filioque’s inclusion in Roman Catholic teaching becomes widespread in western Europe owing to a lasting Papal silence over the Filioque’s use.

1274 A.D. –  Having formally separated itself from the other apostolic churches two centuries earlier over a variety of doctrinal and political issues, the fourteenth council of the Roman Catholic Church (known as the Second Council of Lyon) unilaterally condemns those who deny that the Spirit proceeds eternally from the Father and the Son. This includes all Christian churches not overseen by Rome.

1517 A.D. to the present – The Creed containing the Filioque clause passes into almost all confessions arising after the Protestant Reformation, except for the Creed’s notorious rejection by the Church of Latter-day Saints (Mormons) and the Jehovah’s Witnesses. The Creed itself is not well known among many lay Christians of the modern era.

2003 A.D. –   The officially sanctioned North American Orthodox-Catholic Theological Consultation concludes a four-year study of the Filioque, making non-binding recommendation to all members and hierarchs of the apostolic churches. It recommends that they “enter into a new and earnest dialogue concerning the origin and person of the Holy Spirit.” It also proposes that in the future both Roman Catholics and Orthodox “refrain from labeling as heretical the traditions of the other side” on this subject, and that the theologians of both traditions make a clearer distinction between the divinity of the Spirit, and the manner of the Spirit’s origin, “which still awaits full and final ecumenical resolution” and between issues of theology and church governance.

It also suggests that attention be paid to the status of councils of both churches that took place after the seven Ecumenical Councils of the first Christian millennium. And finally, in view of the fact that the Vatican has affirmed the “normative and irrevocable dogmatic value of the Creed of 381” in its original Greek version, the Consultation recommends that the Roman Catholic Church use the same text without the Filioque “in making translations of that Creed for catechetical and liturgical use,” and should declare that the condemnation pronounced by the Second Council of Lyons [noted above] is no longer applicable.

In the judgment of the Consultation, the question of the Filioque is no longer a “Church-dividing” issue, one that would impede full reconciliation and full communion. “It is for the bishops of the [Roman] Catholic and Orthodox Churches to review this work and to make whatever decisions would be appropriate.”

To date, no Catholic or Orthodox Church has taken official action on the report’s recommendation.