The Bible clearly teaches that God is a Trinity. In other words, there is only one God, but that one God is in three persons: God the Father, God the Son and God the Holy Spirit. One God in three persons; three persons in one God.
Perhaps the most convincing reason for this is that God is love. The Bible doesn't say just that God loves, or that God commends love, but that God is love. Love has to have an object. God could not have existed alone. So before creation began, there were the three persons of the Godhead, loving each other.
As you go through the Bible, it's interesting to notice the ministry, if that's the right word, of each one.
All three were involved in creation. God the Father spoke the word. The second verse in the Bible says the Holy Spirit was there, hovering over the face of the waters. Of the Son of God, the Scripture says that all things in heaven and earth were created by Him; all things were created through Him and for Him (Col 1:16).
All three were involved in the crucifixion, for Heb 9:14 says that Christ through the eternal Spirit offered Himself without spot to God.
And all three were involved in the resurrection. In John 2:19 - 21 Jesus said if they destroyed His body, He would raise it up in three days. Gal 1:1 says God the Father raised Jesus from the dead. And in some translations 1 Pet 3:18 gives us the idea that the Holy Spirit had a part too.
Now here's something amazing. If you are a committed Christian, did you know that it took all three persons of the Godhead to bring you to faith? It was the Holy Spirit who convicted you of sin, for John 16:8 says it is His ministry to convict the world of sin, of righteousness and of judgment. It was God the Father who drew you to Christ, for Jesus said no man comes to Him except the Father draws him (John 6:44). And it was the Son of God who took you in and gave you eternal life.
If you're not yet a committed Christian, Jesus said "I am the door" (John 10:9). He's the way to God. Life without Him is empty. Life with him is abundant. Life with Him is what we were created for. If you want the answer to your problems, come to Christ.