In the last year, I have been presented with several professing Christians who deny that God is indeed a Trinity, one unified being in three distinct persons. This has raised the question: Can one reject the doctrine of the Trinity and consistently present oneself as a Christian? My answer to this question will not surprise regular readers or those who know me well. My answer is a resounding “no!” To deny that God is triune is to deny a doctrine essential and fundamental to the Christian faith. Scriptural language about God, Jesus, and the Spirit is unintelligible without a Trinitarian framework. Early Christian churchmen and theologians recognized this reality and struggled to creedalize the unique scriptural language on the relationship between the God of Israel, Jesus of Nazareth, and the Holy Spirit to preserve for all true Christian fellowships a scriptural and historical doctrine. This doctrine has been affirmed by all major historic branches of the Church – Roman Catholic, Orthodox, and Protestant. Any person who denies the Trinitarian nature of God ought to realize, and be honest enough to confess, that they are parting ways with the way Christianity has historically articulated the doctrine of God. Such persons may think the Church has gotten it wrong when it comes to theology proper; however, they should be truthful enough to admit that the doctrine of the Trinity and the meaning of “Christianity” are so entwined that to deny the former while retaining the latter is inconsistent and misleading.
So, must one believe in the Trinity to be a Christian? Absolutely! I should be clear, though, that mere assent to the doctrine of the Trinity does not make one a Christian. One can believe that God is triune and yet hate him. In contrast, one who has placed his full confidence for salvation in the Jesus revealed in the Bible will also be placing his faith in the God Jesus has definitively revealed, namely the God who is triune. So, it should be understood that believing in the Trinity does not necessarily make one a Christian, but Christian faith is always Trinitarian faith.