Matthew Poole and continuators on 2 Corinthians 1:19

19 For the Son of God, Jesus Christ, who was preached among you by us, even by me, and Silvanus, and Timotheus , was not Yea, and Nay, but in him was Yea .

The Apostle here giveth a reason, why he had made Truth and Sincerity so much his business (which reason obligeth us also, who are as much bound as he, to study a conformity to Christ) saith he, The Son of God who was preached among you, that is, Christ Jesus; (who, though (as some observe) is in these Epistles no where called God, but Lord) is here called the Son of God; which can be understood in no other sense, than by Eternal generation; for those who are only the Sons of God by Adoption, are not the subjects of Ministers preaching. We read of this Silvanus, 1 Thess. 1.1. 1 Pet. 5.21. Some think that he was the same person who is called Silas, Acts 16.19. Of Timothy we have heard before. They were both Ministers, who (as well as Apollos before mentioned) had laboured in the Gospel amongst the Corinthians. Now (saith the Apostle) that Christ whom both I, and other Ministers of the Gospel, have preached to you, is not incertain and inconstant, one thing at one time, and in one place, another thing at another time, and in another place.

He was only one and the same; his Doctrine was always certain and uniform, and consistent with it self; and our conversation ought to be suitable to him and his Doctrine.