"Host of the whole Church" gives the thought that all believers, from whatever country they came, found shelter in his house when they arrived in Corinth.
Saint Demetrius of Rostov holds that he later became bishop in Ephesus.
Concerning the household of Stephanas, Saint Paul writes at the end of this epistle that it was the firstfruits of Achaia.
That is, the members of this house were the first of the Achaeans to devote themselves to the service of the saints, to assist the Gospel and labor together with those laboring in this work.
Stephanas himself, together with Fortunatus and Achaicus, had now been sent to Saint Paul with a letter from the Corinthians, which he answers below (1 Cor 16:15-17).
These, he says, are all who were baptized by me. Whether I baptized anyone else, I do not know.
This turn of speech means a complete denial. He is expressing: I baptized no one else.
I had no concern to baptize. "He did not strive to gain honor from the people by such a deed" (Saint Chrysostom).
My helpers fulfilled this, and even the first converts and baptized.
Undoubtedly not all of the Corinthians were carried away by the crowds of vain wise men, and the persons named by the Apostle, who were baptized by him, did not belong to their circle.
By pointing to them, he speaks as if saying: these people, baptized by me, do not count me as their head.
For what reason have you others fallen into such a sickness of mind, and why do you remain in it?
Come to your senses. Follow in their steps.
That such a thought is fitting is shown by the Apostle's words at the end of the epistle about the household of Stephanas: "You also submit to such people" (1 Cor 16:16).
This thought also accords more directly with his thanksgiving: glory to God that I baptized almost no one.
And those whom I baptized are sound. Not only are they sound, but they will serve to bring others to their senses.