I have enjoyed doing puzzles from the time my aunt sent to me a 500 piece puzzle of the Sound of Music back in the 1980s. As I think about it the church itself is like a puzzle. For the following (at least) 5 reasons.
Uniqueness of Every Piece
In a puzzle, every single piece is a unique piece and fits in only one place. There are many pieces that look like each other but when it comes down to it every piece can fit in only one place. God has created everybody uniquely. If every single human being has a unique physical imprint, they also have a unique spiritual imprint. And each person is useful and necessary in the church as the church is being built. Jeremiah 1:4-5 The word of the Lord came to me, saying, “Before I formed you in the womb I knew you, before you were born I set you apart; I appointed you…”
Parts in the Whole
One piece is not the whole puzzle. The whole puzzle is made up of numerous pieces, and every piece needs its immediate neighbor and its extended neighbors and all the other pieces in order to make one complete picture. There is no lone-ranger Christian. Every Christian needs the other. He needs his immediate neighbors, his distant neighbors and every other Christian to complete the entire universal church. John 10:16 I have other sheep that are not of this sheep pen. I must bring them also. They too will listen to my voice, and there shall be one flock and one shepherd.
Equality of the Components
Some pieces get there first and some pieces get there later. As humans in a local church we may look largely similar but depending on when a person comes to Jesus Christ they may look vastly different. A person who became a believer 20 years ago - and has allowed the Word of God and the Spirit of God to continually change him - will behave significantly different then someone who became a believer last week. This is possible only if the old believer did not continuously rebel against God and submitted to (what is called) the sanctifying work of God-in which the Holy Spirit continues to change that person from the inside out. So it is not that one piece is better than the other. Just like in a puzzle every single piece is as important as the other piece, so also in the church every single piece is as important as the other piece. But some pieces, because of the will of the puzzle maker, get there earlier and sol are more useful in the building up of the puzzle than other pieces. Eph 4:11-13 So Christ himself gave the apostles, the prophets, the evangelists, the pastors and teachers, 12 to equip his people for works of service, so that the body of Christ may be built up 13 until we all reach unity in the faith and in the knowledge of the Son of God and become mature, attaining to the whole measure of the fullness of Christ.
Continuous and Progressive
It is a continuous, progressive work. No substantial, meaningful puzzle is done immediately. The larger, complicated puzzles are done in stages and over time. As it turns out, God tends to do work in stages and progressively. He could’ve made all of creation in a blink of an eye. But He chose to do it in stages, slowly, each successive stage building up on the previous one. For whatever reason, the maker of the puzzle chooses to do one part of the puzzle first - it may be the edges of the puzzle or it may be another predominant section of the puzzle or a part of the puzzle that has similar colors for example. Regardless of where the puzzle starts, the puzzle continues to build on what was previously completed. From the moment it starts it is a continuously, progressive work with each piece building on the previous pieces. This also means that at no point until the very end, is the puzzle complete. And therefore, at no point can anybody look at the church criticize the incompleteness of the church. Ephesians 4: 13 until we all reach unity in the faith and in the knowledge of the Son of God and become mature, attaining to the whole measure of the fullness of Christ. Also, God is faithful and the Church that He starts building, he will complete. Phil 1:6 being confident of this, that he who began a good work in you will carry it on to completion until the day of Christ Jesus.
The Big Picture
The puzzle does not make sense for any of the pieces because they don’t see the big picture. Only the person doing the puzzle knows the big picture. Many times, we as humans apply what we think is logical to the church and try to examine and interpret how God grows the church. There is a certain amount that we can understand but there is a large amount that we don’t understand because it is beyond our human brains. Just like the intention of the puzzle maker cannot be grasped or recognized by the puzzle pieces, even though as human beings with the Spirit of God, we may understand certain things about the mind of God, there are many things that we will not fully understand about God and His church. (cf. 1 Corinthians 2:10). Thus it is impossible for any human being to coherently criticize the workings of the church. Of course, there are times when things go wrong because the church, unlike inanimate puzzle pieces, are made up of sinful humans with free (albeit, imperfect) wills. Unbeknownst to us, there is a pattern to the picture even though the end result is not immediately visible. We may have a vague, hazy view of the church (and spiritual matters in general). 1 Corinthians 13:12 For now we see only a reflection as in a mirror; then we shall see face to face. Now I know in part; then I shall know fully, even as I am fully known.
The clear view will come sometime in the future - when the puzzle and the church is complete.