What Christians Believe about the Trinity Concept. In the simplest of terms, Christians believe there is only one God, and God expresses Himself through His Image and His Spirit. The three Persons are God the Father, His Holy Image (Jesus Christ), and His Holy Spirit. The Bible teaches that God through His Image (Son) and His Spirit are all Eternal and God according to Colossians 2:9. It also shows that The Father is Greater according to John 14:28 and Jon 14:26.