And when he was come, straightway he came to him, and saith, Rabbi; and kissed him ( κατεφίλησεν αὐτόν); literally, kissed him much. The kiss was an ancient mode of salutation amongst the Jews, the Romans, and other nations.
It is possible that this was the usual mode with which the disciples greeted Christ when they returned to him after any absence. But Judas abused this token of friendship, using it for a base and treacherous purpose.
St. Chrysostom says that he felt assured by the gentleness of Christ that he would not repel him, or that, if he did, the treacherous action would have answered its purpose.