The New Testament "Church"
When Paul wrote to the church in Philippi (4:15) he addressed "all the saints in Christ Jesus which are at Philippi, with the bishops and deacons." (1:1)
Saints are "set apart" people, who have come "out of darkness into His marvelous light" (1 Pet. 2:9), who belong to the Lord.(l Cor. 6:20) This is another way of saying that all Christians are saints (in the N. T. sense) and beatification by some Roman council has nothing to do with it.
One does not become a saint by "joining" the church; but one becomes a part of the church by becoming a saint. The church does not save; it is the saved. Thus we read in Acts 2: 47, "And the Lord added to the church ("to them" "together" ARV) daily (day by day) such as should be saved (those that were being saved).
The word church is a collective word, such as "herd" "covey" "flock". Literally, it indicates collection or assembly (called-out people) and is translated "assembly" in Acts 19:32, 39, and 41, with no reference whatsoever to God's people. In some places it refers to saints literally assembled but is perhaps more often used to "collect" figuratively those who have something in common.
All of God's children (the firstborn ones, Heb. 12:22-23) make up the church in its general or universal sense. They are "collected" in this designation because they have something in common -- their relationship to God the Father. They need not know one another, and God authorizes no plan for collective acts. But as each one seeks to serve God through Jesus Christ, he "glorifies God in the church." (Eph. 1:6, 12; 2:6,22; 3:21) The reader is blind indeed who tries to bind these passages to the local organized church.
But there are requirements, and provisions in the N.T., for saints to work together collectively-- to function as a unit. They were to assemble, (Heb.10:25) worship, (1 Cor. 11:22-f.) have overseers (Acts 14:23) a treasury (1 Cor. 16:2) etc. It was to such a group as this that Paul addressed the Philippian letter, and he called them a "church". (Phil. 4:15) This is the local church or congregation—the largest, smallest, and only organization of Christians given divine sanction in the New Testament.
These saints are "collected" by something more than a common relationship to God; they enter into a certain oneness by agreement (Cf.Acts 9:26-28, 3 Jn. 10); discipline one-another (Matt. 18:17 1 Cor. 5); have servants (Rom. 16:1) and send messengers (Phil. 2:25); and in many other ways work as one -- collectively.
Many errors arise because we fail to recognize the N. T. definition of "church" (Ex.: the importance of being a member) or the various uses of the word. (Ex.: some try to make each obligation of the individual saint an obligation of the local church.)
Careful reading "would from many a blunder free us, and foolish notion." Beside that, we might learn something.