Augustine of Hippo — as excerpted in the Catena Aurea on John 6:15-21

“(Tr. xxv. 2) Yet He who feared to be made a king, was a king; not made king by men, (for He ever reigneth with the Father, in that He is the Son of God,) but making men kings: which kingdom of His the Prophets had foretold. Christ by being made man, made the believers in Him Christians, i. e. members of His kingdom, incorporated and purchased by His Word. And this kingdom will be made manifest, after the judgment; when the brightness of His saints shall be revealed. The disciples however, and the multitude who believed on Him, thought that He had come to reign now; and so would have taken Him by force, to make Him a king, wishing to anticipate His time, which He kept secret.”