
I. God being only one
II. God being Triune — Father, Son, and Spirit
III. A mystery of mysteries
First, we must be clear that there is only one God. God is one. There is no other God. Our God is the only God; both the Old and New Testaments make this abundantly clear. Isaiah 45:5 says, "I am the Lord, and there is none else, there is no God beside me." First Corinthians 8:4 says, "There is no God but one." In the whole universe there is only one true God. The God who has a good pleasure, will, eternal purpose, and economy is one. The God who chose us and predestinated us is one. The God who created the heavens, the earth, and man for His purpose is one. The God who loves man is one. The God who became incarnated to die for us so that we might be redeemed, forgiven, washed, justified, and reconciled is one. The God who resurrected to be our life to regenerate, sanctify, transform, conform, and glorify us is one. We have only one God: not two, three, or many, but one.
Although our God is one, there is something mysterious about Him. He is three-one, or "triune" (in Latin, "tri" means three and "une" means one). That is why we call Him the "Triune God." You may wonder where this term comes from, since there is no such number in human mathematics. In Matthew 28:19 the Lord Jesus says, "Baptizing them into the name of the Father and of the Son and of the Holy Spirit." Here the Lord speaks clearly of the three — the Father, Son, and Spirit. But notice that the word "name" is singular. You may even say that the name of our God is "Father, Son, and Holy Spirit." Because of Bible verses like these, we can see that our God is one-yet-three and three-yet-one.
The Triune God (Father, Son, and Spirit) is a mystery — in fact a mystery of mysteries! Small and finite as human beings are, we can neither understand it thoroughly nor define it in a full way. John 1:1 says, "The Word was with God, and the Word was God." By the clause "the Word was with God," we understand that the Word and God are two, for the Word was with God. But "the Word was God" indicates that the Word and God are one, for the Word was God. Are They one or two? They are both. This is a mystery.
Second Corinthians 3:17 says that "the Lord is the Spirit." Here the Lord and the Spirit are one, for the Lord is the Spirit. Then the same verse speaks of "the Spirit of the Lord." This indicates that They are two. Are the Lord and the Spirit one or two? It is a mystery.
Notice that in Hebrews 1:8-9 the Son is addressed as God; then God is referred to as "His" God: "But as to the Son, Your throne, O God, is forever and ever...therefore God, Your God, has anointed You." How can you explain this? Can you say, "O God, Your God"? This is also a mystery.
Finally, in Revelation 1:4, 4:5, and 5:6 we read that the one Spirit of God (Eph. 4:4) is called "the seven Spirits." Here is another mystery. Dear brothers and sisters, we must learn simply to accept the pure Word.
This mystery should not bother us too much, however. Many things relating to life are not understandable to men; we can only have a general idea of them. For instance, although we have life in our physical body, no one can explain this life thoroughly, for it is a mystery. Furthermore, there is a spirit within us — this is even more of a mystery. What is the life of man? And what is the spirit of man? No one can give a full explanation. If we cannot comprehend such a comparatively small mystery as man, we should not expect to be able to fully understand the great mystery of the Triune God — the Father, Son, and Spirit. There are many other unexplainable things in the universe. Electricity is one example. With our limited minds we can only understand that some things are so, but we cannot perceive why they are so. If we cannot fully understand something like electricity, how much less can we understand the Triune God!
Although we cannot understand this mystery of the Trinity of the Godhead, we can receive and enjoy this mysterious God. We cannot understand, but we can enjoy! In former days men had no knowledge of vitamins, yet they greatly enjoyed their benefit. Praise the Lord! The Triune God is not for us to understand, but to enjoy. All that He is for us to enjoy is revealed in the Scriptures. Although we cannot fully understand it, we may, according to all that is declared in the Bible, accept whatever is said and enjoy Him.