Who would have known? If you are missing a piece to a favorite jigsaw puzzle and the manufacturer cannot help by replacing it, then you can contact a company (see Jigsaw Doctor) that will manufacture a replacement piece, even matching the colors and picture of the missing piece.
The difficulty with missing puzzle pieces, of course, is that you can work on the puzzle for quite awhile before discovering a piece is not there. That is like the situation when Paul found twelve believers in Ephesus who were missing part of the Christian story. As we read in Acts 19:1-7, they had gone on for some time not realizing what they were missing, in particular the role of the Holy Spirit.
Whether by divinely inspired discernment or not, Paul gets to the heart of the problem in verse 2, asking, “Did you receive the Holy Spirit when you became believers?” Their reply is probably less drastic than it sounds in English, “No, we have not even heard that there is a Holy Spirit.” Since these were followers of John who had received his baptism, they are almost certainly Jews, which means they could not have failed to hear about God’s Spirit in the Hebrew Scriptures. One would guess that they also heard John himself say about the One to come, as he does in Luke 3:16, “I baptize you with water… He will baptize you with the Holy Spirit…”
We can only surmise that these disciples of John, who have received John’s baptism (verse 3), are missing some key component of the message about Jesus which comes later than John. The missing piece could even possibly be the account of Jesus’ death and resurrection. They almost certainly have not heard about Jesus’ promise of the gift of the Spirit and the events on Pentecost.
So these believers in Ephesus are pleasantly surprised to learn that their faith includes much more than they had imagined. The work of the Holy Spirit in their own lives is a wholly unknown and unexpected benefit available to them upon good instruction and proper baptism that includes the name of Jesus (almost certainly the Trinitarian formula prescribed by Jesus Himself). The gifts of tongues and prophecy in verse 6 demonstrate that they truly did then experience the gift of the Holy Spirit.
With a complete New Testament and many centuries of Christian witness available to us, it is unlikely that we are missing some key element of Christian doctrine which ought to be included in our faith. However, we may at a practical level be functioning as if we have not heard the whole story. Acting as if one has not heard of the Holy Spirit may be a rather common Christian deficiency, as we fail to rely on the Spirit’s guidance, gifting and comfort. We may need to recall again that His work in us is in fact included in Christian life. When we are trying to put our lives together, the Spirit should not be a missing piece of the puzzle.