Inquiring minds—both Christian and non-Christian—can hardly be blamed for wondering, three what and one what? and is this a contradiction? Then there is the problem that the words Trinity and triunity cannot be found in Scripture. Nor can the whole concept be found explicitly spelled out in the Bible. And to compound the problem, the trinitarian doctrine (as contrasted with belief in God as triune) took decades, almost a century, to carve out and perhaps never was completely settled. Unfortunately, some Christians have become so exasperated by the seeming confusion surrounding belief in the Trinity—that God is one divine being eternally existing as three distinct persons—that they have functionally given up on it. They may be members of a church with the word Trinity in its name; they may pay lip service to belief in something called Trinity if asked; they may sing a hymn about God’s triunity now and then in worship. But fewer and fewer Christians seem actually to embrace the belief known throughout Christian history as Trinity. As one modern Catholic thinker has said, modern Christians tend to be functionally unitarian.

(Roger E. Olson, Mosaic of Christian Belief: Twenty Centuries of Unity & Diversity, Downer Groves, Illinois: IVP Academic, 2002, 133-134; Excerpt from Chapter 6)