John 6:70,71

“ Jesus answered them: Is it not I who have chosen you the Twelve?And one of you is a devil! Now he spoke of Judas, the son of Simon, Iscariot, for he it was that should betray him, he, one of the Twelve. ”

Peter had spoken in the name of all; Jesus tears off the veil which this profession, apparently unanimous, threw over the secret unbelief of one of their number. Not only does He wish thereby to make Judas understand that He is not his dupe and prevent the offense which the thought that their Master had been wanting in discernment might cause to the other apostles.

But He desires, especially, to awaken Judas' conscience and to induce him to break with the false position in which he seems to persist in continuing. Jesus addresses in His answer, not Peter alone, but all (αὐτοῖς, them). He brings strikingly together (καί) these two facts so shockingly contradictory: the mark of love which He has given to them all by their election and the ungrateful perfidy of one of them. The words ἐξ ὑμῶν have the emphasis: “From among you, chosen by myself.” The word διάβολος, does not mean merely diabolical, or child of the devil (John 8:44); it denotes a second Satan, an incarnation of the spirit of Satan. The word of address: Satan, addressed to Peter in the scene at Caesarea Philippi, makes him also an organ of Satan. But as for him, he was so only momentarily and through an ill-directed love. This Judas, to whom Jesus had just opened the door, nevertheless remains, covering himself with the mask of a hypocritical fidelity and accepting as his own Peter's profession. The term which Jesus had employed expressed already the deep indignation which was occasioned in Him by this persistency of Judas and the foreseeing of the hateful end to which this course of action must infallibly lead him.