God the Father has a form and a shape of a man, he looks exactly like me and you. Jesus has a form and a shape of a man, he lives in a human body, the same body which was crucified, dead and buried and raised back to life. The Holy Spirit does not have a form; throughout the scriptures he took different forms, his shape was based on the work which he was doing at that particular moment. In Exodus 14:21 he appeared as the wind that parted the red sea into two, in Exodus 13:21 he appeared as a pillar of cloud by day, and fire by night. In Joshua 5:14 he appeared as the captain of the Lord's army. He appeared to Jacob and wrestled with him as the angel of the Lord, he fertilized the womb of a virgin without a male sperm to form baby Jesus, he was the one behind every miracle in the entire Bible.
The Holy Spirit is a person, he is not a thing or some power, he is a person like Jesus and the Father. He has a mind, emotions and a will. He is the hand through which the Father and Jesus work in the earth. No work of God can be done without the Holy Spirit; he is the only way to carry out the Lord’s work. Without the Holy Spirit there is no Christianity, you can never have a church without him, any church planted without the Holy Spirit is nothing but a social club or a group of people who meet to read the Bible and sing songs. That you go to church every Sunday does not mean anything to God, it is your relationship with him that matters. The only way to have that relationship is through the Holy Spirit. Nothing you do for God will be acceptable to him except it is done through the Holy Spirit.
1 John 5:7 says; there are three that bear witness in heaven, the Spirit, the Water, and the blood. Salvation in Christ is only consummated by these three, the Spirit, the Water and the blood. The blood is for the remission of sin; Water is symbolic of baptism into his death and resurrection. The Spirit baptism means the indwelling presence of the Holy Spirit within your spirit. God himself comes to live in you through the Holy Spirit.