Abandoning the prohibition of evil because one falls into similar deeds
The one who is addicted to programs that are haram (forbidden) on television should strive to quit. This can be done through strengthening of his faith by first connecting with the book of Allah, then the mosque, and lastly staying in the company of righteous people until he remains under the watch of Allah. This will hinder him from watching bad movies that can make him fantasize on ways of masturbating or doing other secret illicit acts.
The sin of the one who calls to the path of Allah should not cause him to abandon the enjoining of good and forbidding of evil. This is obvious as the act of abandoning is also a sin. Continuing with the calling in the path of Allah will make him fear of becoming one of those who advise people to do right, but forget themselves; or to be among those who normally preach what they do not do (their words do not correspond with their actions) and thus falling into that which is despicable in the sight of Allah as in Qur’aan 61:3.
The basic principle for every preacher is for them to exhibit what they preach. As Allah says in Qur’an 11:88 “…and I do not intend to differ from you in that which I have forbidden you…” about the story of Prophet Shuaib. And this should be a model for him while he is alone and when in public.