John Calvin Commentary 2 Corinthians 1:19

"For the Son of God, Jesus Christ, who was preached among you by us, [even] by me and Silvanus and Timothy, was not yea and nay, but in him is yea." — 2 Corinthians 1:19 (ASV)

For the Son of God. Here we have the proof—because his preaching contained nothing but Christ alone, who is the eternal and immutable truth of God. The clause preached by us is emphatic. For, as it may be, and often does happen, that Christ is disfigured by human inventions and adulterated, so to speak, by their disguises, he declares that this had not been the case with himself or his associates. Instead, he had sincerely and with fitting integrity presented Christ pure and undisguised. Why he makes no mention of Apollos, while he names Timothy and Silvanus, is not entirely clear; unless the reason is, as is probable, that the more individuals were assailed by the slanders of the wicked, the more careful he was to defend them.

In these words, however, he intimates that his whole doctrine was summed up in a simple acquaintance with Christ alone, as indeed the whole of the gospel is included in it. Therefore, those who teach anything other than Christ alone go beyond proper limits, with whatever display of wisdom they may otherwise be puffed up. For as he is the end of the law (Romans 10:4), so he is the head, the sum—in short, the consummation—of all spiritual doctrine.

In the second place, he intimates that his doctrine respecting Christ had not been variable or ambiguous, so as to present him from time to time in a new shape after the manner of Proteus. Some people make it their sport to make changes to him, just as if they were tossing a ball to and fro with their hand, simply to display their dexterity. Others, in order to gain the favor of men, present him in various forms, while still another class teaches one day what they retract the next day out of fear. Such was not Paul’s Christ, nor can the Christ of any true apostle be such. Therefore, those who paint him in various colors for their own advantage have no ground to boast that they are ministers of Christ. For he alone is the true Christ, in whom there appears that uniform and unvarying yea, which Paul declares to be characteristic of him.