Years ago I talked with a Jehovah’s Witness. They believe the Father is God and that Jesus is His first created being. He said he couldn’t understand the trinity (one God in three persons). Why would God be something we couldn’t understand he said? I asked him if he could completely understand the common cold. He said no. If you cannot understand part of the creation, how could you hope to understand the very nature of the Creator? He had no answer for that.

     A while ago I talked with a Mormon friend. They don’t believe in the trinity. He told me I was telling him that 1+1+1=1. I said no, I’m telling you that 1x1x1=1.

     I’ll be honest, the trinity, the very nature of God, is hard to understand. But that doesn’t mean its not true. The Jews one sentence compilation of the essence of their faith is Deuteronomy 6:4 (the Shema). It says, “Hear O Israel: the Lord our God, the Lord is one”. In the Hebrew language, the word ‘one’ has two words for it.  The Hebrew word ‘yachid’ means one, as in only one. The Hebrew word ‘echod’ means one as in a unity, like one bunch of grapes. Guess what Hebrew word for one is used in Deuteronomy 6:4? If you guessed ‘echod’, you’d be right.
Isaiah 45:5,6 says “I am the Lord, and there is no other; apart from me there is no God….I am the Lord and there is no other.” In the Old Testament, its pretty clear that there is only one God.

     In Genesis 1:26, God says “Let us make man in our image, in our likeness…” Then on verse 27 it says, “So God created mankind in his own image…” This only makes sense if God is a trinity. Some will say in verse 26 that God is using the ‘royal we’ but there’s no indication of this as no one else is mentioned in this context. Some will say God is referring to Himself and the angels. But that’s an assumption without any proof. And remember, God doesn’t share His glory with anyone (Isaiah 42:8).
All we have to do is prove that there is one God (a unity) but that there’s three people called God (a tri-unity or a trinity).

     In Exodus 3:14 when Moses asks God who should he say sent him to Pharaoh, God tells Moses His personal name. We translate it as “I am”. In John 8:58, Jesus takes the very name of God (“I am”) for Himself. The Jews understood what He was doing and took up stones to kill Him as He was making Himself equal to God, which was blasphemy.

     God is called the ‘alpha & omega’ (the first and the last) in Isaiah 41:4  44:6 & 48:12. Yet Jesus is also called this in Revelation 1:7,8  2:8 & 22:13,16. You can only have one ‘first’ and one ‘last’.

     In John 1:1  the Word is called God but in verse 14 the Word is identified as Jesus.

     In Hebrews 1:8 God (the Father) is calling the Son (Jesus) God.

     In Hebrews 1:3 it talks about the Son being the radiance of God’s glory and the exact representation of His being. Also see Colossians 1:9. But remember that Isaiah 48:11 says God won’t share His glory with anyone. Then in John 17:5,24 God shares it with Jesus.

     In Exodus 3:14, we are told to worship only God but in Matthew 2:2,11  28:9,17 & John 9:38 & Hebrews 1:6 Jesus receives worship.

     If there is no trinity, how can Jesus and God be called the same things? This would be a contradiction in the scriptures.

     In regards to the Holy Spirit as God, in John 14:16 the Holy Spirit is called ‘another comforter’. In the Greek language, the word ‘another’ has the prefix ‘homo’ attached to it. ‘Homo’ means the same as while ‘heteros’ means a different kind. This is clearly Jesus’ reference to the deity of the Holy Spirit.
The Holy Spirit has the  same attributes as God has. He is eternal (Hebrews 9:14) and all-knowing (1^st Corinthians 2:10, 11). The Bible says that lying to the Holy Spirit is lying to God (Acts 5:3,4).

     While there is much more proof for both the deity of Jesus Christ & the Holy Spirit, it should be pretty clear that three persons in the Bible are called God: the Father, the Son (Jesus) and the Holy Spirit…yet there is only one God. God is called a unity, yet three people are called God (a tri-unity or a trinity). So yes, we Christians do worship one God. That one God is Father, Son and Holy Spirit.