Among the wicked spirits, there are some that are more cunning than others. They are not content with leading only us into sin, but instill into us thoughts to make others our accomplices in evil, so as to afflict us with harsh torment. I have seen a person transmit his sinful habit. Later, coming to his senses, he began to repent and abandoned his sin. However, because the person that learned his bad habit did not cease to sin, the repentance of the former was in vain.
Saint John Climacus