He is timeless, He requires no form or sustenance. Yet, He created Man in His image. I believe this means that we have mind, spirit and free will. There may be other qualities we share. He has Mind, Spirit and a Human form.
Humans have a mind, spirit and body.
He chose to reveal Himself to us in human form so that we could make a connection with Him, and so that He could become the sin sacrifice for our sins. It was this Human Incarnation which makes it possible for us to have a relationship with God for eternity. Christians do not worship three gods. We worship one God who has revealed Himself through a human incarnation, and who inhabits his believers as the Holy Spirit. Evidently, even ancient Jewish writings discuss the possibility of the trinity.