I was told for years that the Greek word for “church” (ἐκκλησία) simply meant a “gathering”… that all a church is, is a bunch of (pretty) random Christians getting together; Whether you know them or not, as long as they’re christians and you’re reading the bible, its a “church gathering”.
But look at Acts 14:26-27 (or Acts 15:30)
“From Attalia they [Paul and Barnabas] sailed back to Antioch, where they had been committed to the grace of God for the work they had now completed. On arriving there, they gathered the church together and reported all that God had done through them and how he had opened a door of faith to the Gentiles.”
Notice what they did; they “gathered (συναγαγόντες)” people. This is the normal word in Greek for gathering or a crowd. But… whom did they gather?
They gathered the church (ἐκκλησίαν). So ἐκκλησία can’t simply mean “a gathering” of people; the word identifies a group of people, a party, a family… who can be gathered.
Certainly, one of the signs of being a member of an ἐκκλησία is that you do gather. But being one of those who gather does not make you part of the ἐκκλησία, any more than coming over to my place for dinner makes you part of my family.
Take away message: 1. If you’ve been told that your “local church” doesn’t exist when it’s not gathering (as I was told at College), don’t worry – it does. (See also Elwell, Walter A. “Church” in “Evangelical Dictionary of Theology” 1997).
2. Who do you gather (συναγαγὴ) with? Are they your church (ἐκκλησία)? Or are you just attending their gathering?