While there are problems with these uses of the term "church," they all share the common theme of people who are gathered together. Someone who knows the language of the New Testament could even point out that the word translated "church" has the literal meaning of people called out and called together.
Ah, but that is the heart of the very serious problem some of us seem to have! Church is a place. A building. A set of Sunday observances. An event performed by a group. Indeed, God's people are the church whenever they are together for song and prayer, Scripture and communion, hospitality and proclamation. But God's people are meant to be scattered as well as gathered.
It is a mistake to think the worship life of the church is principally a Sunday-focused event. It is the whole life of the whole church reaching into the whole world that Paul had in mind writing this:
Present your bodies as a living sacrifice, holy and acceptable to God, which is your spiritual worship (Romans 12:1 ESV).
Everything in the life of a Christian should be seamlessly appropriate for putting God's heart and character on display. Yes, the church is sometimes a gathered community. More often, however, it is what one medieval scholar called "the community of the dispersed." The arena within which the church functions to put the holiness and justice of God on display is the whole world — for whose sake it is called to be light and salt. If the church is the church only when it is within four walls, who is doing God's work in your office, plant, or neighborhood?
Luis Palau makes this point with a metaphor most of us would understand. He says the church is like manure. Spread it around, and it will give life, make things grow, and produce fruit. Keep it all piled up in one place, and it stinks!
Kindergarten teachers, bank presidents, computer geeks, maintenance people, teens, senior citizens — all of us can be intentional about bringing light into dark places. Giving hope to discouraged souls. Acknowledging the lonely. Being representatives of God's loving presence in all the places we inhabit or visit.
Whatever you do or say, do it as a representative of the Lord Jesus, giving thanks through him to God the Father (Colossians 3:17 NLT).