The Bible has to be interpreted in light of the Trinity.
The overarching theme of the Bible is the Father/Son relationship. In fact, the entire Bible is a full description of this relationship between Father and Son, as God wants to see it in us. We know this because of the testimony of the best authority in the Bible - Jesus himself, the eternal Son of God. The reason he came was to gather a Family together and make them one with himself, in his image, so that they might become Sons of God.
Seen in this light, both the Old Testament and the New Testament are revelations of the eternal Trinity of Father/Son/Holy Spirit, and can't be properly understood except in that light.
(Excerpt taken from Biblical Theology for Pastors and Teachers