To the church of God that is in Corinth, to those sanctified in Christ Jesus, called to be saints together with all those who in every place call upon the name of our Lord Jesus Christ, both their Lord and ours ... -- 1 Corinthians 1:2
The church is the ekklesia -- those who are called out. Our English word church is derived from a different Greek word, kyriakon, from the root kyrios -- lord or master, thus "the lord's house". The physical structure of a building is not holy. It serves a holy purpose. I think a building can develop a holy atmosphere, but it is the saints meeting together in the presence of God that sanctifies a place. No place can sanctify us. This is probably harder for some believers to grasp than for others. Churches with altars and iconography that have been sanctified should be respected and may be venerated, but we are respecting and venerating not the thing itself, which is nothing, but the faith, love, and devotion of those who set it apart, and in which, by the grace of God, we may participate. God dwells in believers, not stained glass windows or statues or cathedrals.
Because Corinth was such a messed up place, this letter spends a lot of time talking about what the assembly of believers ought to look like, how they ought to behave, and what they really are. It addresses, point by point in some cases, a variety of questions raised by the local, mostly Greek converts. Paul, in his linguistically skillful, systematic way, introduces the main point at the start. We are the church; we are God's people. We are sanctified, made holy and chosen in Christ. We are called to be holy and called together. The only legitimate divisions are geographic ones. The world, as we shall see further on, will find plenty of reasons to be offended by Christianity, but we should seek to live as inoffensively as possible both with those inside the Body of Christ and those outside.
The verse quoted could be broken down like this: we are the called-out, called to be saints, who call upon the name of our Lord, Jesus, the Chosen and Anointed One who was called to save us.
That's a lot of calling, but that's what God does.
We live out in the country, and we have a volunteer fire department. It is not entirely such as we have some full-time staff, but most of the firefighters and emergency personnel are not just sitting around the firehouse. They are available and ready to answer the call when it comes in.
We're kind of like that. We are on-call. We do other things. We have a building where we meet every so often for training, strengthening, and encouragement, where we sometimes rally in order to be properly equipped. We don't actually do our work there any more than firefighters only put out fires down at the station. Now we are different from the volunteer firefighters in that things are not always on fire, and we are not responding only to emergency situations. Our work is done daily and everywhere in everything that we do, because, as we are indwelt by the Spirit, we are carrying God into every task that we address and every place that we visit.
That can be a sobering thought for some of us.
We are, or ought to be, learning to give more and more of our lives to the Lord each day. Saints are not plaster. There are supposed to be a lot of them. Jesus said (Matthew 10:34-36) that He would bring division even in families. The truth may divide us from those who cling to delusions and deceptions, to the idols and false gods of their own creation. Yet the true joy and, of course, the calling, of saints is in fruit-bearing and multiplication. Take the call.