The Institutes, Book 7
The Example of Judas
Would you like to know how dangerously and harmfully that incitement, unless it has been carefully rooted out, will shoot up to destroy its owner and put out branches of every kind of sin? Look at Judas, counted among the number of the apostles. See how, because he would not crush the deadly head of this serpent, it destroyed him with its poison; and how, when he was caught in the snares of craving, it drove him into sin and a headlong fall, so that he was persuaded to sell the Redeemer of the world and the author of man’s salvation for thirty pieces of silver. He could never have been driven to this monstrous sin of betrayal if he had not been tainted by the sin of greed. Nor would he have made himself wickedly guilty of betraying the Lord unless he had first got into the habit of robbing the bag entrusted to him.