Luke 3:21-22 (ESV)
21 Now when all the people were baptized, and when Jesus also had been baptized and was praying, the heavens were opened, 22 and the Holy Spirit descended on him in bodily form, like a dove; and a voice came from heaven, “You are my beloved Son; with you I am well pleased.”
At the baptism of Jesus, the heavens were opened. They were opened to the flesh of man through the obedience of Jesus, the Son of Man. This allowed the the Holy Spirit to descend to the earth and enter Jesus in bodily form.
God entered the flesh of man through through the power of the Holy Spirit. Through the obedience of Christ, the heavens were opened and the Holy Spirit descended bodily into the flesh of man. Thus Jesus would become the exact image of God in creation. He was the begotten Son of God in the form of man who came to dwell among us.
The body of Christ received the fullness of the Holy Spirit at His baptism of the water of repentance, though the He was without sin. This was done to fulfill the way of the righteousness of man. He opened the doors of heaven and showed us the way to pass through them.
When He ascended into heaven in bodily form, the Spirit went with Him. With the flesh of man raised into heaven, the Spirit of God would return to earth and be given to the new body of Christ, which are those who believe in Jesus and His work of the salvation of man.
When the time is right, those in the body of Christ will likewise ascend in bodily form into heaven to be with Christ. The Holy Spirit will return from the earth in bodily form which is the body of Christ.
John 14:15-17 (ESV)
Jesus Promises the Holy Spirit
15 “If you love me, you will keep my commandments. 16 And I will ask the Father, and he will give you another Helper, to be with you forever, 17 even the Spirit of truth, whom the world cannot receive, because it neither sees him nor knows him. You know him, for he dwells with you and will be in you.