Your body is the physical temple which God has given you to dwell in while here on earth. The Soul is the core of your being, the part of you which holds personality, memories, emotion, etc. It is who you are - Adam became a "living soul." The spirit is your immaterial nature which, though the body dies, lives beyond the grave. Even our being is a type of trinity. See how it's possible? You are a living soul and your existence is made up of three distinct parts (body, soul, and spirit). God is also one God and eternally lives in the persons of the Father, Son, and Holy Spirit. God did say, "let us make man in our image", and we've been make like Him in more than just a physical sense.
I'm not attempting to make this thread a trinity debate, but you should be able to see the relation here. It is possible for God to have three separate persons and inseparablly be one God. We have a finite human mind and in our mind it seems impossible, but nothing is impossible with God. He is greater than us and He draws near to Himself those He chooses. That's grace, nothing we have done. Those who do not believe that Jesus Christ, the Son of God, is God have been blinded and do not know the Father because they do not know the Son. The scriptures say that if you do not believe the Son, you also do not believe the Father and you make God to be a liar because you don't believe the Son whom He has sent. Eternal life is believing in Jesus Christ. If you believe Him, you will love His holy commands and live for Him.
Jesus said to Philip, “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’? (Jn 14:9)
And Thomas answered and said to Him, “My Lord and my God!”
Jesus said to him, “Thomas, because you have seen Me, you have believed. Blessed are those who have not seen and yet have believed.” (Jn 20:28,29)