Realising that the doctrine of God is fundamental to all of Christian theology and life, we should pause to focus on one of the most distinctive aspects of the Christian doctrine of God: the idea that God exists in Trinity.
Unbelievers have sometimes accused the church of inventing this doctrine, saying that it can’t be found in the Bible. But Christians have always insisted that the doctrine of the Trinity is fully scriptural. So, where does the Bible teach this important doctrine?
Well, the truth of the Trinity, which is that God is as truly “they” — three persons — as he is “he.” It’s awkward to say it in terms of grammar, but that’s how the New Testament puts it really. The truth of the Trinity is there in solution in the New Testament in the way that if I stir sugar into my cup of tea, the sugar is there in solution, in the liquid. And the truth of the Trinity was crystallised out of the New Testament through all sorts of queries and debates about it that occupied the church for the first four centuries after the Lord had risen and the Spirit had come.
You can say it this way, you have the Lord Jesus as the focus of faith and discipleship, but the Lord Jesus distinguishes himself from his heavenly father at whose command he is on earth administering. He is himself, God to be worshipped. When finally after his resurrection Thomas says to him, “My Lord and My God,” he doesn’t say, “Now don’t call me that.” He accepts it. “My Lord and My God” is the right way to acknowledge who he is. But he is distinct from his heavenly Father. And then, before he left his disciples, he promised that he would send the Holy Spirit, as someone distinct from himself and from the Father. He says both that the Father sends the Spirit and that he himself sends the Spirit. So there you are.
In the teaching of the Lord Jesus you’ve got the three persons. And in the teaching of the apostles, you’ve got the three persons. As I said, the doctrine is in solution throughout the whole New Testament. And when it has to be crystallised, well, out comes the formula, “he” is “they” — Father, Son, and Spirit — and “they”— Father, Son, and Spirit — are “he,” the one God. It’s mysterious; we don’t know how it can be. But from biblical testimony, which is unambiguous; we know that it is. And there are lots of things in Christianity of which one has to say the same thing — truths about God — I don’t know how it can be, but I know that it is because the Bible tells me so.