The doctrine of the Trinity, far from being a peice of abstract speculation, is actually the inevitable conclusion to which the church was driven by the logic of theo-drama. The church fathers soon came to realize that the integrity of the gospel is fatally compromised if either the Son of the Spirit is not fully God. If the Son were not God, he could neither reveal the Father nor atone for our sin. If the Spirit were not God, he could unite us neither the Father and Son nor one another. The gospel, then, requires a triune God. The God of the gospel reveals and redeems precisely as Father, Son, and Spirit.
Kevin Vanhoozer, The Drama of Doctrine: A Canonical-Linguistic Approach to Christian Theology, p. 43