Paul, no concept of the universal church? The early church met in houses (Acts 2:42-46, Acts 5:52, etc.), at the riverside, in the marketplace, at the temple, etc. Addressing a city meant addressing the believers in that city, not one specific building. It's our modern church that's crazily divided into different denominations and often acts like the local building is the 'church' rather than the entire body of Christ. Paul always treated local groups as part of the larger unified body of Christ.
But let's look at Paul's actual words on the church:
"Just as a body, though one, has many parts, but all its many parts form one body, so it is with Christ.
For we were all baptized by one Spirit so as to form one body—whether Jews or Gentiles, slave or free—and we were all given the one Spirit to drink. Even so the body is not made up of one part but of many." I Cor 12:13-14
Were the Corinthians the only ones to be baptized by the Spirit? Are the Corinthians alone in the body of Christ?
"But in fact God has placed the parts in the body, every one of them, just as he wanted them to be. If they were all one part, where would the body be? As it is, there are many parts, but one body." I Cor 12:20
Are the Corinthians the only believers to be diverse parts in the body of Christ? Is the rest of the church monolithic?
"But God has put the body together, giving greater honor to the parts that lacked it, so that there should be no division in the body, but that its parts should have equal concern for each other. If one part suffers, every part suffers with it; if one part is honored, every part rejoices with it." I Cor 12:24-26
Is the Corinthian church unique in its need to give equal concern to parts with different gifts? Is Corinth alone the only church group God put together?
"Now you are the body of Christ, and each one of you is a part of it. And God has placed in the church first of all apostles, second prophets, third teachers, then miracles, then gifts of healing, of helping, of guidance, and of different kinds of tongues. Are all apostles? Are all prophets? Are all teachers? Do all work miracles? Do all have gifts of healing? Do all speak in tongues ? Do all interpret? Now eagerly desire the greater gifts." I Cor 12:27-31
Is Paul teaching Sola Corinth - that Corinth alone is the body of Christ? Is Paul saying that only Corinth has apostles, teachers, healers, etc.?
"Love never fails. But where there are prophecies, they will cease; where there are tongues, they will be stilled; where there is knowledge, it will pass away. For we know in part and we prophesy in part, but when completeness comes, what is in part disappears. When I was a child, I talked like a child, I thought like a child, I reasoned like a child. When I became a man, I put the ways of childhood behind me. For now we see only a reflection as in a mirror; then we shall see face to face. Now I know in part; then I shall know fully, even as I am fully known. And now these three remain: faith, hope and love. But the greatest of these is love." I Cor 13:8-13
Is Corinth the only church that needs to understand what love is? Are prophecy, tongues, and knowledge only to cease someday at Corinth? Are the believers of Corinth alone the ones to someday see face to face? Are the Corinthian Christians alone to have hope?
"I thank God that I speak in tongues more than all of you. But in the church I would rather speak five intelligible words to instruct others than ten thousand words in a tongue." I Cor 14:18-19
Is Paul saying that this is true only in Corinth, and that if he goes elsewhere he'd prefer speaking ten thousand words in tongues rather than giving instruction?
By the way, the word Ecclesia he is using is not limited to the local church.
Ecclesia means "called out from/to" - that is, called out from the world and to God.
https://biblehub.com/greek/1577.htm
"Tongues, then, are a sign, not for believers but for unbelievers; prophecy, however, is not for unbelievers but for believers. So if the whole church comes together and everyone speaks in tongues, and inquirers or unbelievers come in, will they not say that you are out of your mind? But if an unbeliever or an inquirer comes in while everyone is prophesying, they are convicted of sin and are brought under judgment by all, as the secrets of their hearts are laid bare. So they will fall down and worship God, exclaiming, “God is really among you!”"
I Cor 14:22-25
Are tongues a sign for unbelievers only at Corinth, but a sign for believers elsewhere? Is prophecy for believers only at Corinth, but for unbelievers elsewhere? Is everyone speaking in tongues more intelligible if it isn't done at Corinth? Is prophesying less convicting if it isn't in Corinth?
"What then shall we say, brothers and sisters? When you come together, each of you has a hymn, or a word of instruction, a revelation, a tongue or an interpretation. Everything must be done so that the church may be built up. If anyone speaks in a tongue, two—or at the most three—should speak, one at a time, and someone must interpret. If there is no interpreter, the speaker should keep quiet in the church and speak to himself and to God. Two or three prophets should speak, and the others should weigh carefully what is said. And if a revelation comes to someone who is sitting down, the first speaker should stop. For you can all prophesy in turn so that everyone may be instructed and encouraged. The spirits of prophets are subject to the control of prophets.
For God is not a God of disorder but of peace—as in all the congregations of the Lord’s people." I Cor 14:26-42
If this instruction is based in God being a God of order, and God is a God of order in *all* the assemblies of the saints, then wouldn't the premise of order be equally applicable? Even if exact rituals slightly vary, the instruction of "order" and the purpose of "edification" should apply anywhere.
And Paul's last comments which ensure this isn't "just" for Corinth and that Corinth doesn't get to operate by different rules than everyone else:
"
Or did the word of God originate with you? Or are you the only people it has reached? If anyone thinks they are a prophet or otherwise gifted by the Spirit, let them acknowledge that what I am writing to you is the Lord’s command. But if anyone ignores this, they will themselves be ignored. Therefore, my brothers and sisters, be eager to prophesy, and do not forbid speaking in tongues. But everything should be done in a fitting and orderly way." I Cor 14: 36-40
The problem with Corinth is that it was *deviating* from the rules for the whole church and not caring about order. Paul's instruction was to correct their misunderstanding - not say that they alone and no other church group needed to be orderly and respect those with different gifts.