I don't see how one could believe the bible does NOT teach the concept of the trinity.
It is surprising that within all of the to and fro there has been no discussion of the concepts of Appropriation and Perichoresis that are critical in understanding and reconciling God's one-ness with three distinct hypostases. I suppose this is in part because of the superficial nature believing that everything one needs to know about God and the understanding of His plan can be found exclusively within the truncated Bible of the Reformation applying only those thoughts that originate within ourselves. But that violates the Greatest commandment to love God with all of our hearts, all of our minds, and all of our souls.
Once the Trinity us better understood it becomes obvious that in His plan for Redemption we cannot appropriate for ourselves the criteria for good and evil and what is true and what is false. When we do those things we appropriate to ourselves the Divine Life rather than receiving it. The Divine Life is a gift from God, not a right of inheritance or a wage for sitting in the right pew. Understanding the Trinity, moves us to a closer and more dependent relationship with the Logos.
Peace be with you