Whether one agrees with it in toto or not, one of the few serious and constructive works on evangelical prolegomena, is John R. Franke's The Character of Theology: A Postconservative Evangelical Approach.
John's theological journey and contribution is to be watched carefully. One might find weaknesses here or there [John would probably be the first to admit it], but one cannot seriously engage contemporary evangelical theology and ignore his work.
Chapter two is entitled, "The Subject of Theology." John writes, "For Christians, the subject of theology is the God revealed in Jesus Christ. Accordingly, the Christian answer to the question of God's identity ultimately leads to the doctrine of the Trinity…the confession of the Triune God has been the sin qua non of the Christian faith" (p. 45). He continues, "the trinitarian conception of God is so closely tied to the biblical narrative that it serves as a shorthand way of speaking not only about the God of the narrative but also about the narrative itself as the act of the God of the Bible" (p. 46).
On this the church must speak with one voice.