Theologian Charles W. Lowry has called the doctrine of the Trinity "the most comprehensive and the most nearly all-inclusive formulation of the truth of Christianity." I happen to agree with him profoundly.
Many scholars actually believe that the bulk of truly Christian doctrine is nothing more than "an extended commentary" on Christ's reference to God as Trinity in the Great Commission (cf. Matthew 28:19-20). No truly missional conversation can advance without this "extended commentary."
It should be noted that "name" in Matthew 28 is singular, which prompted Karl Barth to strikingly call this (Father, Son and Holy Spirit) the "Christian name" of God. And contemporary theologian Thomas Oden has added, "From the time of the apostolic fathers, triunity has been considered definitive of Christian teaching of God, accepted alike by Protestants, Catholics, and Eastern church communions . . . . It is not merely speculative or theoretical or incidental or optional teaching, but is regarded by consensus as essential to the Christian understanding of God."
You will often hear certain Reformed and Lutheran conservatives cite Luther's famous line that justification by faith alone is the article by which the church stands or falls. They will do this to insist that they are true churches while all others are not. Given the context of Luther's statement, and the times in which he said this, I concur with the statement at face value, though I want to make sure it is contextually understood. But I think it is a mistake to say that justification by faith alone (especially understood in this very narrow way) is the real article of the faith by which the Church stands or falls. That article has to be the truth of the Trinity, the name of the Christian God. Here everything distinctly Christian stands or falls. Without this article of faith there is no Christianity, no faith. The tragedy is that multitudes of conservative Christians either do not know this or if they do they do not much care.
On June 16 the first of my several articles on the Trinity in my E-zine series, called the ACT 3 Weekly, will be published online. If you do not subscribe use this link and at the top of the home page sign up for these. I hope these articles will underscore just how important this truth is and show us how we might regain its vital life-giving power in the Church.