Romans 16:23

That is, the one who received me in his house. Furthermore, that Gaius received in his home the whole Church and Paul himself, this is great praise; for Paul would not have gone to him if he had not found him worthy. The steward and …

Then he says: Caius, my host, was the person to whom John wrote in his third letter commending the charity he exercised toward the saints; and the whole church, namely, who were assembled in his house or who were in that region. Then he says: …

It was no disparagement to the chamberlain of the city to be a preacher of the gospel of Christ. Quartus is likewise mentioned, and called a brother; for as one is our Father, even Christ, so all we are brethren. Description of the Gospel;

It would appear that he was one of only two persons whom Paul baptized with his own hand (compare 3Jo 1). His Christian hospitality appears to have been something uncommon. Erastus the chamberlain--"treasurer." of the city--doubtless of Corinth.

Gaius mine host - Gaius in Greek is the same as Caius in Latin, which was a very common name among the Romans. St. Luke (Act 19:29) mentions one Gaius of Macedonia, who was exposed to much violence at Ephesus in the tumult excited by Demetrius the silversmith against St. Paul and his companions; and it is very possible that this was the same person. He is here called not only the host ξενος, the entertainer of St. Paul, or Tertius, (if he wrote this and the following verse), but also of the whole Church: that is, he received and lodged the apostles who came from different places, as well as the messengers of the Churches. All made his house their home; and he must have been a person of considerable property to be able to bear this expense; and of much piety and love to the cause of Christ, else he had not employed that property in this way. Erastus the chamberlain of the city - Treasurer of the city of Corinth, from which St. Paul wrote this epistle. This is supposed to be the same person as is mentioned Act 19:22. He was one of St. Paul’s companions, and, as appears from 2Ti 4:20, was left about this time by the apostle at Corinth. He is called the chamberlain οικονομος, which signifies the same as treasurer; he to whom the receipt and expenditure of the public money were intrusted. He received the tolls, customs, etc., belonging to the city, and out of them paid the public expenses. Such persons were in very high credit; and if Erastus was at this time treasurer, it would appear that Christianity was then in considerable repute in Corinth. But if the Erastus of the Acts was the same with the Erastus mentioned here, it is not likely that he now held the office, for this could not at all comport with his travelling with St. Paul. […]

Gaius mine host - Who has received me into his house, and shown me hospitality. The word “host” means one who entertains another at his own house without reward. And of the whole church - Who has opened his house to entertain “all” Christians; or to show hospitality to them all. He was baptized by Paul himself at Corinth 1Co 1:14; and was so highly esteemed by the church that John wrote an epistle to him; 3Jn 1: