references to house churches in the NT
...and to the church in thy house, Philemon 2
Likewise greet the church that is in (Priscilla's and Aquila's) house, Romans 16:5
Aquila and Priscilla salute you much in the Lord, with the church that is in their house, 1 Cor. 16:19
Salute the brethren which are in Laodicea, and Nymphas, and the church which is in his house, Colossians 4:15
If by two or three witnesses a matter is established, there is enough evidence to convict here. Granted, two of the verses reference the same church. But that is just the point, is it not a church that is referenced?
Conceding that two of the references above concern the same church, we are left with only three witnesses to the existence of house churches in the New Testament. Fortunately for us, that is still above the legal minimum for establishing the truth of a matter.
Brethren, we do not need more witnesses than this. It is self-evident that churches met in houses in the days after Pentecost. There had been no time, nor the money to erect any edifices for the convergence of the saints. But fortunately, none were necessary. They had living rooms!
It is perceived a shortcoming of these churches that, due to seating limitations, church growth might be suppressed or discouraged. We do not hear anything from the apostles in this regard. I imagine the saints just broke off into separate assemblies. Remember, the saints in any locale were addressed by Paul as "the church," and we do not take it that all met in one place, do we? They may, or they may not have, as the situation dictated.
Too many Christians today evaluate New Testament churches through the lens of ecclesiasticism. That is, man's traditions and not New Testament practices, has colored perceptions. Ecclesiasticism is not taught, it is just practiced. It is a set of traditions, mostly corrupt. Paul was careful to distinguish the traditions of men from the apostolic traditions, the latter which had the advantage of being inspired by God. Paul wrote concerning head coverings and prayer in the church, "If any man seem to be contentious, we have no such custom, neither the churches of God." I Cor. 11:16. Is it, then, legalism to contend for these customs? Then Paul was a legalist.
Christians do not need a building, they do not need a pastorate, they do not need organization, in order to meet in houses on the Lord's day. They have authority to meet from our Lord, who said, where two or three assemble in His name, He is in their midst. If that is not a church at its most elemental, then what is it? It is duly constituted on the authority of Jesus Christ. By that standard many churches fail. Our Lord removes lampstands at will, formerly not without advance warning (Rev. 2), presently on the basis of revealed truth. But where two or three assemble in His name, I take it there is a lampstand. If Christ is there, there must be a lampstand.