The central doctrine of most Protestant and Catholic churches for many centuries has been that of the Trinity.
This doctrine is so important that the Catholic Encyclopedia states: "This (the Trinity), the Church teaches, is the revelation regarding God's nature which Jesus Christ, the Son of God, came upon earth to deliver to the world: and which she (the Catholic Church) proposes to man as the foundation of the whole dogmatic system."
Both Catholic and Protestant theologians quote Theophilus of Antioch (circs 180 A.D.) as the first person to write about this most important doctrine. But isn't it strange that such a major doctrine was avoided in religious writings for nearly 200 years? That is almost as long as the United States has been a nation!
Furthermore, Theophilus' allusion to the traditional trinity -- "the Father, the Son and the Holy Spirit" is quite nebulous at best.
Notice what Theophilus wrote in commenting about the 4th day of creation in the first chapter of Genesis: "And as the sun remains ever full, never becoming less, so does God always abide perfect, being full of all power, and understanding, and wisdom, and immortality, and all good. But the moon wanes monthly, and in a manner dies, being a type of man; then it is born again, and is crescent, for a pattern of the future resurrection. In like manner also the three days which were before the luminaries, are types of the trinity, of God and His Word, and His Wisdom" (Ante-Nicene Fathers, "Theophilus to Autolycus").
Here is the first statement by a theologian that is supposed to teach the doctrine of the Trinity. But does his statement really teach this? Read it -- simply. He does not say that God is a trinity of persons, or that the Holy Spirit is a part of that trinity. He just refers to God, His Word and His Wisdom.
Theologians have tried to imagine into this unusual statement "their trinity" and yet even the editors of the Ante-Nicene Fathers state in a footnote that the word translated "wisdom" in English is the Greek word Sophia which Theophilus elsewhere used in reference to the Son, not the Holy Spirit.
Theophilus could not possibly have gotten the idea of a Trinity from the Bible, if he really did have a trinity of persons in mind, which appears unlikely from the preceding statement as the Bible nowhere even alludes to God being a Trinity.
From the time of Theophilus, it was several hundred years before this doctrine became a part of the Catholic dogma. It was in the last 25 years of the 4th century that "what might be called the definitive Trinitarian dogma 'one God in three persons' became thoroughly assimilated into Christian life and thought" (New Catholic Encyclopedia, "Holy Trinity").
From this it is evident that this "central doctrine" of Catholicism and Protestantism was not a part of the "faith which was once delivered unto the saints" (Jude 3) during or prior to the time of Jude, but was added by later theologians.
The doctrine of the Trinity was not what Jesus Christ "came upon the earth to deliver to the world." He came to preach the Good News of His soon-coming Kingdom, to establish His true Church, to give His life as a sacrifice for all who repent, and to give God's Holy Spirit to those who are baptized, the Spirit that empowers believers to be one with the Father and the Son!