As the subject suggests, I want to ask about the Trinity. Given that the Trinity is never explained, described, or mentioned in the Bible then why do you believe in it?
1) The material substance of the doctrine of the Trinity is grounded in Scripture.
2) The idea that something has to be explicitly stated or spelled out in the Bible for it to be true and credible is a concept that is alien to the entire Christian experience and enterprise. There isn't a single Christian, of any perusasion or any kind, that actually operates with this as a consistent metric of "doing" theology. Case in point: No where in the Bible do we have the Canon of the Bible "explained, described, or mentioned"--the very existence of the Bible, as a Canon of Scripture, is itself
extra-biblical.
3) Christian faith is grounded in Jesus Christ, His Person and Work and Teaching, and the ministry and teaching of the Apostles, which by the power of the Holy Spirit made others disciples and believers in this same Jesus; this Christian faith is the communal possession of the Church of Jesus Christ, and the Scriptures which the Church has received, believed, and confessed as Holy--i.e. the Bible--is the Chief Witness of this faith. Among Christians the precise relationship of Scripture within the Sensus Fidei is not monolithic and uniform; but speaking as a Lutheran, the Lutheran Confession is that Scripture alone (Sola Scriptura) is the Unruled Rule (Norma Normans) which governs the whole of Christian life, faith, and practice. That is, that which is contrary to Scripture must be rejected, for Scripture rules over all else; that all else, when and because it is faithful and ruled over by Scripture, is called the Ruled Rule (Norma Normata), and is to be believed, received, and confessed because it is faithful--it is faithful to Scripture, faithful to the teaching of Christ and the Apostles, faithful to the whole work and provenance of God who has, from the beginning, working all things toward that good end which is in Christ for the whole world.
So I believe the Trinity because:
1) It is biblical.
2) It is Christian.
3) It is true.
-CryptoLutheran