John Chrysostom
It is dangerous, beloved, dangerous to fall into the depth of evils. Then it becomes difficult for the soul to be corrected.
Therefore one must strive in every way not to be caught at the beginning, for it is easier not to enter into evil than, after entering it, to amend oneself.
Look at Judas. Once he cast himself into evil, no matter how much help he receives, he does not rise.
Christ said to him, "One of you is a devil." He said, "Not all believe" (Jn 6:70, 64). He said, "I do not speak of all of you," and, "I know whom I have chosen" (Jn 13:18).
Yet he feels none of this.
"So when He had washed their feet, taken His garments, and reclined again, He said to them, 'Do you know what I have done to you?'" He now says this not to Peter alone, but to all.