I Corinthians 1:16

And I baptized also the household of Stephanas: besides, I know not whether I baptized any other (KJV)

Then: Stephanus and his household were the first fruits of Achaia (see chapter 16:15). Paul just remembered that he'd baptized them too, but the letter writer didn't have a computer - just papyrus and stylus. He couldn't go back and change what was just written because something jogged Paul's memory (Baker, p.30). Paul did remember - he was just a little slow at it. But once remembered, Paul is still focused on making his point. The person who does the baptizing is not important. Christ is. And these people are way off track bickering over which party - those of Cephas, those of Apollos, of Paul, or even of Christ. Everyone is united with and in the same Holy Spirit. Christ is not divided.

Now: Obviously, no building can be constructed to hold all the people in an area at the same time. Geographic subdivisions and scattered meeting places have to happen. From the beginning though, divisions seem to be the name of the game - groups within the Catholic church and subdivided denominations are everywhere. Everyone is convinced that "their" church is best. We know better because of Paul's teachings and because of Christ. I can't solve that problem - but I can speak peacefully to fellow disciples.

Extra source: Cornerstone Biblical Commentary 1 Corinthians (William Baker), 2 Corinthians (Ralph Martin & Carl Toney), ed. by Philip Comfort. Carol Stream: Tyndale House Publishers, c2006.