The greatest argument for the Trinity, is not to show verses that Jesus is God. Many who deny the deity of Christ, and consequently the Trinity, have no problem with Jesus being called God. They say there is only one True and Living God and Jesus represents Him. As Moses would be like God to Aaron (Exodus 4:16), they would say that Jesus would be like a God to us. They would say that Jesus is not THE God, but He is A God (i.e. Godlike).
The best approach is to show that Jesus is Jehovah. He is the LORD, the true and living God of the Old Testament, which is quite easy to demonstrate. Today, we are going to show one passage that does that (along with many more), Romans 9:33, which quoted Isaiah 8:14. Today, we will hopefully give compelling reasons, many reasons, why Jesus is not only the True and Living God, the one God of the Scriptures, but also that the Father and the Holy Spirit are likewise that one God. The term “Trinity” speaks of a Tri-unity and the best definition of what that entails is found in the Westminster Shorter Catechism and its restatement in the Baptist Catechism which says the following
Q. 8: Are there more gods than one?
A. There is but one only, the living and true God.
Q. 9: How persons are there in the Godhead?
A. There are three persons in the Godhead, the Father, the Son, and the Holy Spirit; and these three are one God, the same in essence, equal in power and glory. – The Baptist Catechism
Why is this such a good definition? It is because it follows the way God reveals Himself to us in the Bible. In the Old Testament the oneness of God is stressed. In the New Testament we learn of the Father, the Son, and the Holy Spirit, and we learn that the Father is God, the Son is God, and the Holy Spirit is God. However, there is a distinction between the three persons: The Father is not the Holy Spirit, the Holy Spirit is not the Son, and the Son is not the Father (see the triangle-circle diagram). The best way to visualize how the three relates to the one is to see the three persons being inside the one essence of God. Have you ever seen a pre-made cookie mix where you slice the rolled cookie dough into cookies and place them on a cookie sheet? THIS IS NOT WHAT IS HAPPENING WITH THE TRINITY. We are not to cut up the one divine essence into three parts and call each part a person. You would end up we three gods. The essence of God remains one. It is not divided!
Years ago, a person sought to join the church. She professed faith in Christ as her Savior. I was so glad to hear that. I asked her to read our confession of faith (1689 London Baptist Confession). Afterwards, I asked her if she had any questions and she told me that she did not believe that Jesus was God, and she did not believe in the Trinity. It necessitated picking up this topic in teaching and preaching. That was a long time ago. It is time once again to teach about this important doctrine. Would you like to know more about it and why it is so vital to our faith?