Peter tells us that we are "being built up a spiritual house." Paul speaks about "being fitted together." From these statements we must conclude that the building process is continually taking place. What is this building? What is actually happening?
Perhaps the following example can help us. Suppose a group of believers comes together for the first time and introduces themselves to each other. Let us assume that each one has a real relationship with God. They have been baptized into the body of Christ by the Spirit; thus, they are one with each other because they have partaken of God's life. There is a perfectly open relationship between each member as they meet each other and begin to get acquainted.
The question we pose is this: At this time, is this group of believers "built together"? In other words, do they function as one under the authority of Christ? I think most would agree that the potential is there, but realistically, the requirements Christ could put upon them as a body of believers is minimal. They hardly know each other! They have not yet established spiritual relationships with each other. This will take time. Not only must they get to know each other, they must go through things together. Their relationships in Christ need to be established and proven.
Now suppose we visit this same group of believers 20 years later. In those 20 years, they have gone through many things together. There have been trials and testing as they have faced the demands of life. Children have grown up. Some members may have died. There have been many opportunities to bear each other's burdens, caring for their brothers and sisters. Some may have turned aside from the faith. New ones have been added as they reached out to a needy world. There have been misunderstandings that had to be cleared. There may have been wrongs committed that had to be forgiven. As they lived through these and many other things, close relationships have been established. In the words of Paul, they have been "fitted together."
What meaning does all of this have to God? In this later place of greater maturity as a body of believers, God can now direct them to move as "one man" under the authority of Christ for a fuller manifestation of His life. He can put greater demands upon them as a body because they have been cemented together in the love of God and have grown up a "spiritual household." The members know each other according to the Spirit. There is a level of trust built that allows them to be available to God and to each other in a way they were not in the beginning. Even though they were willing in the beginning, they were not yet built together as a habitation of God in the Spirit.
Can we see from this simple example that this building together which must take place is very real? Not only is it real, it is very important to God because it takes a many-membered body to express the life of God. The very nature of God (love) is expressed by a body, not by a single member. The love of God may be in the heart of every member, but the thought behind the "household" is that love must be demonstrated to be seen. The function of the household or the body in a given locality is to express the character and nature of God as He directs.
If we consider these things in light of our human experience, we must acknowledge that these things are not simple. To interact with fellow believers and allow God to build spiritual relationships takes the grace of God. These things take time and spiritual effort. Apart from Christ, people choose a few friends to develop relationships with, and they do so on the basis of natural affinities. God does not allow us to pick and choose, but requires us to develop relationships with all who are in Christ. All natural ties must be purposely laid aside. Our relationships are solely because we are in Christ. When we dwell closely with others, character flaws and weaknesses are soon revealed, and God must be allowed to deal with them. This is all part of God's plan for our growing up into Christ.
In light of these things, consider Paul's instruction to the Ephesians. "Therefore, putting away lying, 'Let each one of you speak truth with his neighbor,' for we are members of one another. 'Be angry, and do not sin': do not let the sun go down on your wrath, nor give place to the devil. Let him who stole steal no longer, but rather let him labor, working with his hands what is good, that he may have something to give him who has need. Let no corrupt word proceed out of your mouth, but what is good for necessary edification, that it may impart grace to the hearers. And do not grieve the Holy Spirit of God, by whom you were sealed for the day of redemption. Let all bitterness, wrath, anger, clamor, and evil speaking be put away from you, with all malice. And be kind to one another, tenderhearted, forgiving one another, even as God in Christ forgave you" (Ephesians 4:25-32).