Openly before the churches,
Of your love
And of our reason
τὴν οὖν ἔνδειξιν τῆς ἀγάπης ὑμῶν καὶ ἡμῶν καυχήσεως ὑπὲρ ὑμῶν εἰς αὐτοὺς ἐνδεικνύμενοι εἰς πρόσωπον τῶν ἐκκλησιῶν.
Paul said that openly before the other churches (εἰς πρόσωπον τῶν ἐκκλησιῶν), you should show (ἐνδεικνύμενοι) them (εἰς αὐτοὺς) the proof of your love (τὴν οὖν ἔνδειξιν τῆς ἀγάπης ὑμῶν) and of our reason for boasting about you (καὶ ἡμῶν καυχήσεως ὑπὲρ ὑμῶν). Only the Pauline writings used this word ἔνδειξιν and the word ἐνδεικνύμενοι, that means pointing out or indication, a proof, a demonstration, or a sign, and the word καυχήσεως that means a boasting, the act of boasting, glorying, or exultation. Paul wanted the Corinthians to show how generous they were compared to all the other Christian community churches. They should show their love and at the same time help Paul with his boasting about them. Paul was egging on the Corinthian community to be generous to show up the other Christian communities. He had told them how generous the Corinthians were. Now it was their turn to prove it. Have you ever been part of a friendly church rivalry?