The foundation of the church is a Person: Jesus Christ (1Co 3:11); building on any other ground produces other things: religious organizations and social clubs, but not the church.
To ensure Christ is the foundation we must think carefully about why we’re meeting; the reasons we assemble comprise this foundation; our motives spawn all our activity and will be God’s focus in judgment. (1Co 3:13) If we don’t engage for the right reason we might defile Christ’s church, and that’s a dangerous thing to do. (1Co 3:17)
So, are we coming to hear uplifting sermons? Or to worship God and enjoy His presence? Or to invite others to hear the gospel? These are all good things, but they aren’t the foundation of the church. We can do these things for Christ, and we can enjoy and seek Him in them, but this isn’t the same as having Jesus Christ Himself as the foundation, the very reason we are coming together. There’s something even more important at the core of the church. (He 10:24-25)
To be a church, believers must be meeting for Jesus Christ, about Jesus Christ: He must be the reason we’re coming together, to bring the indwelling Christ to each other (Col 1:27), to share Him with each other so we can help each other in our walk with Him. (1Co 14:26) We must be coming to see and hear Him in each other (Php 1:21), and to help each other draw closer to Him (Php 2:4), focusing on getting to know Jesus Christ, and Him crucified. (1Co 2:2)
In such community there can be no place in our lives for willful sin (1Jn 3:6), and we should be in close enough community that hiding our sin isn’t an option.
In Christ’s church we cannot delegate this responsibility to edify one another to a few leaders, and sit by passively, expecting them to teach us and bring Christ to us; we each carry this responsibility. (1Th 5:11)
Jesus Christ was the foundation of the very first church, when The Twelve were following Jesus, listening to Him, watching him, beholding Him, studying Him, imitating Him. (1Jn 1:1-3) Jesus Christ was all they had in common; they were pursuing Him; He was their reason for being together. For the church of Jesus Christ, no other reason is acceptable.
Why we come to church affects the leadership style, the order of service, the programs, the budget and all the activity. If in our coming Jesus Christ isn’t building believers into a living network through us, creating a temple He indwells (1Co 3:16), then we’re building on the sand. When the storms come, and they will, nothing will be left. (Mt 7:26-27)