In the account of the baptism of Jesus (Matthew 3), it is clear that John did not understand why Jesus was coming to him for baptism. God had revealed to John who Jesus was, and he knew he was unworthy to baptize Jesus. "But Jesus answered and said to him, 'Permit it to be so now, for thus it is fitting for us to fulfill all righteousness.' Then he allowed Him" (Matthew 3:15). I believe we see here a picture of God's plan, first displayed in Jesus, the "firstborn among many brethren." Jesus was God, so He did not need to repent of sin or be filled with the Holy Spirit like we do. But because it was necessary for Him to be perfected as the Son of man, the Author of our salvation, He submitted first to John's baptism--and ultimately to Calvary--to fully identify Himself with those He came to save (see Hebrews 2:10-18, 5:8-9). God gave His approval, as the Holy Spirit descended on Him to remain. From the very beginning, Jesus did not move on His own, but only in perfect union with the Father, led by the Holy Spirit.
What Jesus did first as the forerunner of our salvation became a reality for us also on the day of Pentecost. Jesus commanded the disciples not to depart from Jerusalem until they were endued with power from on high. They obeyed His command, and not many days later they were all filled with the Holy Spirit. Until Jesus had paid the price of our redemption at Calvary, God could not come to abide within man. But on the day of Pentecost, God the Holy Spirit came to abide within a new temple. He came in fullness, and they were all filled to overflowing.
The people gathered in amazement to behold what was taking place. What they saw and heard was rivers of living water flowing from the throne of God through human vessels, overflowing to the glory of God. But the promise was not just for a few. The door was open for all men, women and children to enter into the glory of God in fullness. Peter told his listeners that if they would repent and be baptized, they also would receive the Holy Spirit. He said that the promise was not only to them, but also to "as many as were afar off." I believe that refers to all believers down through the ages and to the present.
Writing to the Ephesians, Paul prays this prayer: "For this reason I bow my knees to the Father of our Lord Jesus Christ, from whom the whole family in heaven and earth is named, that He would grant you, according to the riches of His glory, to be strengthened with might through His Spirit in the inner man, that Christ may dwell in your hearts through faith; that you, being rooted and grounded in love, may be able to comprehend with all the saints what is the width and length and depth and height--to know the love of Christ which passes knowledge; that you may be filled with all the fullness of God" (Ephesians 3:14-19).
Although the door has been opened for men to enter into this fullness, it is not automatic that they will do so. Paul prayed specifically that the Ephesian believers might be filled with all the fullness of God. The way we enter into this fullness is also contained in Paul's prayer: "to be strengthened with might through His Spirit in the inner man, that Christ may dwell in your hearts through faith." Jesus opened the door, but by faith we must walk through that door to partake of the riches of God. God has provided; faith receives. Faith is God's way for us to experience the riches He has provided.
John says, "...and of His fullness we have all received." The thought here is not that every believer is perfected in maturity when the Holy Spirit comes to abide, but that when we are united with God, the fullness of God is open to every believer. There is no reserve or limit on God's side. Every limitation is on our side. The Holy Spirit has been poured out without measure, and God is no respecter of persons. We often limit the experience of God's fullness through unbelief and disobedience, but it need not be so. Consider this statement of Jesus: "Most assuredly, I say to you, he who believes in Me, the works that I do he will do also; and greater works than these he will do, because I go to My Father. And whatever you ask in My name, that I will do, that the Father may be glorified in the Son. If you ask anything in My name, I will do it" (John 14:12-14).