The Gospel of Barnabas

'There have been and are in the world men who hold not thought for sin; who are in the greatest error. Tell me, how sinned Satan? It is certain that he sinned in the thought that he was more worthy than man. Solomon sinned in thinking to invite to a feast all the creatures of God, whereupon a fish corrected him by eating all that he had prepared. Wherefore, not without cause, saith David our father, that "to ascend in one's heart setteth one in the valley of tears." And wherefore doth God cry by Isaiah his prophet, saying: "Take away your evil thoughts from mine eyes?" And to what purpose saith Solomon: "With all thy keeping, keep shine heart?" As God liveth, in whose presence standeth my soul, all is said against the evil thoughts wherewith sin is committed, for without thinking it is not possible to sin. Now tell me, when the husbandman planteth the vineyard doth he set the plants deep? Assuredly yea. Even so doth Satan, who in planting sin doth not stop at the eye or the ear, but passeth into the heart, which is God's dwelling. As he spoke by Moses his servant, saying: "I will dwell in them, in order that they may walk in my law."
  'Now tell me, if Herod the king should give you a house to keep in which he desired to dwell, would ye suffer Pilate, his enemy, to enter there or to place his goods therein? Assuredly no. Then how much less ought ye to suffer Satan to enter into your heart, or to place his thoughts therein; seeing that our God hath given you your heart to keep, which is his dwelling. Observe, therefore, that the banker considereth the money, whether the image of Caesar is right, whether the silver is good or false, and whether it is of due weight: wherefore he turneth it over much in his hand. Ah, mad world! How prudent thou art in thy business, so that in the last day thou wilt reprove and judge the servants of God of negligence and carelessness, for without doubt thy servants are more prudent than the servants of God. Tell me, now, who is he who examineth a thought as the banker a silver coin? Assuredly no one.'