Summary: There is one God, but three personal expressions of the one undivided, infinite, and eternal nature of God.
The Oneness of God
In Deuteronomy 6:4-5 we read a verse that every Jew has cherished the Shema Israel - (Shema Israel, Adonai Eloheinu, Adonai echad) "Hear, O Israel: The Lord our God, the Lord is one! You shall love the Lord your God with all your heart, with all your soul, and with all your strength. There is but one and only one God manifested in three distinct persons in perfect harmony. God’s whole and undivided essence belongs equally, eternally, simultaneously, and fully to each of the three Persons of the Godhead, so that the Father, Son, and Holy Spirit each is fully God while each is his own personal expression, in role and activity, of the one eternal and undivided divine essence. There is one God, but three personal expressions of the one undivided, infinite, and eternal nature of God. By "nature," the Father, Son, and Holy Spirit, each is equally God, and each is fully God, as each possesses fully the one undivided nature. Yet each is a different Person, and as such, each is different in role and position within the Godhead. The Father is supreme in authority, the Son under the Father, and the Spirit under the Father and the Son. Not three God’s but one God in three Persons, blessed Trinity.
I. The Triune Godhead
A. The Trinity is Scriptural.
1. F.F. Bruce said, "Let us not be misled by the foolish argument that because the term "Trinity" does not appear in the Scriptures, the doctrine of the Trinity is therefore unscriptural.”
2. The Eternal Godhead is revealed in the Word of God as one God existing in three persons; the Father, the Son, and the Holy Spirit. All three are co-eternal, co-equal and co-existent in attributes, power, nature and glory.
3. Genesis 1:26-27 “And God said, Let us make man in our image, after our likeness: and let them have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creeps upon the earth. So God created man in his own image, in the image of God created He him; male and female created He them.
4. Deuteronomy 6:4 “"Hear, O Israel: The Lord our God, the Lord is one!”
5. Matthew 28:19 “Go therefore and make disciples of all the nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit”
6. 2 Corinthians 13:14 “The grace of the Lord Jesus Christ, and the love of God, and the communion of the Holy Spirit be with you all. Amen.”
B. The Father is God
1. 1 Chronicles 17:13 “I will be his Father, and he shall be My son; and I will not take My mercy away from him, as I took it from him who was before you
2. Isaiah 9:6 that he is called the Everlasting Father. This passage however is referring to Jesus and refers to Him as being the father of salvation.
3. Psalm 89:24-26 “But My faithfulness and My mercy shall be with him, and in My name his horn shall be exalted. Also I will set his hand over the sea and his right hand over the rivers. He shall cry to Me, ’You are my Father, My God, and the rock of my salvation.’”
4. Isaiah 63:15-16 “Look down from heaven, and see from Your habitation, holy and glorious. Where are Your zeal and Your strength, The yearning of Your heart and Your mercies toward me? Are they restrained? Doubtless You are our Father, Though Abraham was ignorant of us, And Israel does not acknowledge us. You, O Lord, are our Father; Our Redeemer from Everlasting is Your name.”
5. In the New Testament there are 43 references to God as Father in the Gospel of Matthew alone.
C. The Son is God
1. Isaiah 9:6 For unto us a child is born, unto us a son is given: and the government shall be upon his shoulder: and his name shall be called Wonderful, Counselor, The mighty God, The everlasting Father, The Prince of Peace.
2. John 1:1, 14 “In the beginning was the Word, and the Word was with God, and the Word was God… And the Word became flesh and dwelt among us, and we beheld His glory, the glory as of the only begotten of the Father, full of grace and truth.
3. Colossians 1:16 “For by Him all things were created that are in heaven and that are on earth, visible and invisible, whether thrones or dominions or principalities or powers. All things were created through Him and for Him.”
4. John 14:8-11 “Philip said to Him, "Lord, show us the Father, and it is sufficient for us." Jesus said to him, "Have I been with you so long, and yet you have not known Me, Philip? He who has seen Me has seen the Father; so how can you say, ’Show us the Father’? Do you not believe that I am in the Father, and the Father in Me? The words that I speak to you I do not speak on My own authority; but the Father who dwells in Me does the works. Believe Me that I am in the Father and the Father in Me, or else believe Me for the sake of the works themselves.