Nontrinitarian views differ widely on the nature of God, Jesus, and the Holy Spirit. Various nontrinitarian philosophies, such as Adoptionism, Monarchianism, and Subordinationism existed prior to the establishment of the Trinity doctrine in AD 325, 381, and 431, at the Councils of Nicaea, Constantinople, and Ephesus.[7] Nontrinitarianism was later renewed by Cathars in the 11th through 13th centuries, in the Unitarian movement during the Protestant Reformation, in the Age of Enlightenment of the 18th century, and in some groups arising during the Second Great Awakening of the 19th century.
The doctrine of the Trinity, as held in mainstream Christianity, is not present in the other major Abrahamic religions.
The problem with trinitarian vs. nontrinitarian will never go away because of the lack of evidence for the Trinity doctrine in the Bible.