The concept of fulfillment refers to something that is filled up or brought to completion; thus, filled where it is lacking.
The term “fulfillment” is often employed in relation to the completion of a prophecy. In Matthew 1:22, Mary, a young virgin betrothed to Joseph, became pregnant apart from knowing a man so that Scripture could be fulfilled in what it lacked concerning the prophecy that a virgin will bear a Son and call His name Immanuel. The part of this prophecy that was fulfilled related to a virgin being found with child. In Matthew 2:15, Joseph is instructed to flee to Egypt, fulfilling what the LORD spoke through the prophet: “Out of Egypt I will call my Son.” This type of fulfillment is used because the actions bring the prophecy to completion by providing what it lacked—the events coming to pass.
Fulfillment is also used concerning a person’s actions relating to doing what is righteous. In Matthew 3:15, Jesus is immersed by John the Baptizer. At first, John refuses, recognizing that he needs to be immersed by Jesus. However, Jesus asks him to permit it to be done to fulfill all righteousness. How was righteousness filled up where it was lacking? It was time for Jesus to enter into His priestly service according to the Melchizedek order. For this to happen, He needed to be immersed to enter into service to God (Hebrews 7:11). As a shadow of heavenly things, the Levitical Priesthood showed the necessity of immersion before entering temple service (Exodus 29:4).
As Jesus explains the kingdom of the heavens in Matthew 13:47–50, He uses the term “filling” where “lacking” is used, related to a fishing net. When the fishing net is full of fish, it is drawn in (Matthew 13:48). When calling out the Pharisees for being hypocrites, Jesus states that they are witnesses against themselves that they are sons of those who murdered the prophets, filling to the full the measure of their fathers (Matthew 23:31–32).
Filling where lacking is distinct from filling in a mentally controlling manner. In the upper room on the day of Pentecost, the room where the disciples met was filled with the sound of a mighty rushing wind (Acts 2:2). This sound signaled the coming of the Holy Spirit. With the house filled with the sound of the wind, in the appearance of tongues of flames of fire that sat upon each of their heads. The Holy Spirit then mentally controlled (πίμπλημι) them to speak in other dialects (Acts 2:4). This filling describes a full mental control of a person. It relates to the manner in which the Holy Spirit came upon men before the dispensation of Grace. Once the dispensation of grace has been fully implemented—its steward, Paul, has been training and is teaching the household the rules—the Holy Spirit’s relationship with those of the Church changes from a mental control to a filling where lacking (Ephesians 5:18).
Because our English versions do not distinguish between the two Greek words for fulfillment confusion results, leading to a misunderstanding of Scripture. This befuddlement is seen in the, often misunderstood, events in the upper room used by some to justify the teaching that speaking in another language as a requirement for salvation. In the upper room on the day of Pentecost, the disciples did not receive a Spiritual gift of speaking in tongues. Spiritual gifts fill a person where they lack (1 Corinthians 14:32). In the upper room, the Holy Spirit mentally controlled them to give a sign to Israel (Acts 2:6–8). Many did not continue to speak in tongues after this day. This sign is repeated when Peter brings the gospel of the resurrected Lord to the Gentiles, and the Holy Spirit falls upon them as a sign to the Jews. The Jews with Peter recognized the sign as the same one that was done among them in the upper room (Acts 10:44–46).
When something is filled where it lacks, this type of filling either relates to being filled to capacity, such as a fishing net, or being brought to completion, as with prophecy. When a person is filled where he lacks, he is given the ability to perform a duty he otherwise could not complete.
