Albert Barnes Commentary 2 Corinthians 2:9

"For to this end also did I write, that I might know the proof of you, whether ye are obedient in all things." — 2 Corinthians 2:9 (ASV)

For to this end also did I write. The apostle did not say that this was the only purpose of his writing—to persuade them to excommunicate the offender. He does not say that he wished, arbitrarily, to test their willingness to obey him, or to persuade them to do something inherently wrong, merely to test their obedience.

But the meaning is this: This was the main reason why he wrote to them, rather than coming personally to them. The matter ought to have been addressed; the offender ought to have been punished. And Paul says that he adopted the method of writing to them, rather than coming to them in person, to give them an opportunity to show whether they were disposed to be obedient.

And the sense is, "You may now forgive him. He has not only been sufficiently punished and shown suitable penitence, but another objective I had in view has also been accomplished. I desired to see whether you, as a church, were disposed to be obedient. That objective, also, has been accomplished. And now, since everything aimed at in this case of discipline has been achieved, you may forgive him and should, without hesitation, receive him again to the bosom of the church."