This must be the profoundest of themes. We are concerned with the nature of God Himself.  We can hardly approach such a subject other than with reverence and humility.

In spite of its importance the subject tends to be overlooked by Christians today.  Witness the few books on it in the Christian book store in comparison with other subjects.

Regular reference to God who is Father, Son and Holy Spirit is secured by liturgical formulae such as the ascription of glory at the end of public worship.

The word "Trinity" does not appear in the Bible but Trinitarian formulae do: Matthew 28:19; 2 Corinthians 13:14. The doctrine is in evidence in the Old Testament in such verses as Genesis 1:26, but Old Testament references are implicit and become plain as they are interpreted in the light of the New Testament. The divinity of Christ is plain from the New Testament (see John 1:1 & 14) as is the personality of the Holy Spirit (see John 16). We shall not refer to the many texts which affirm or imply the divinity of the Son and the Spirit because we shall come to them in later studies.

The doctrine of the Trinity distinguishes Christianity from (a) vague speculation about a supreme being; (b) other religions; and (c) "Christian" cults. There is no genuine Christianity without the doctrine of the Trinity.

We need to define what we mean by Trinity. We affirm that:

(i) God is one in essence. See Deuteronomy 6:4. In saying that the Father is God and the Son is God and the Spirit is God, we do not mean that there are three Gods. That is the over simplistic logic that is used to deny the Trinity by those who are of a mind to do so. A pleasing illustration of the unity of God is the cube which has three dimensions without any one it would not be a cube, but which three dimensions are but one cube. Needless to say this illustration is inadequate. No thing that is made can ever be sufficient to speak of the One who is not made and by whom all things else are made.

(ii) God is in three persons. He is not three people! The word persons is grossly inadequate but is intended to designate distinct being with capacity for relationship, communication and knowledge. The Father is not the Son and the Son not the Spirit. The Father loves the Son and the Son the Spirit, and so on. (Immediately this should make us aware that it is false to say that God needed to make man in order to have someone to love. God is complete in Himself. The doctrine of the Trinity will help us in much doctrinal controversy.)

The doctrine of the Trinity speaks to us concerning:

1. Revelation. We need God's self revelation in Holy Scripture in order to know Him. Where else will we find this doctrine? We will not come to it by nature or by unaided reason. We need the Bible if we are to know the truth.

2. Religion. We have to worship the true and living God. If we worship other than the Triune God we worship a false god. Do we dare not worship Jesus if He is God? Our worship has to be Trinitarian if it is to be right. The worship of a God who is not Father, Son and Holy Spirit is idolatry. We worship not a graven image but a mental image.