Praise be to Allah.
There are varying degrees with regard to the Muslims denouncing evil actions. Some have to deal with the evil action by their hands (i.e., by taking action), such as the imaam or leader, or his deputy to whom he has given authority, e.g. a father with his children, a master with his slave, a husband with his wife, if the person who is committing the sin cannot be stopped in any other way. Some people are obliged to deal with the evil action by giving advice, teaching others, telling them off, rebuking them or calling them in a manner that is best, without taking action or using force, lest that provoke fitnah (tribulation) and spread chaos. Some people have to respond to the evil action in their hearts only, because they are too weak to take action or speak out – and that is the weakest of faith. The Prophet (peace and blessings of Allaah be upon him) explained that in his hadeeth:
“Whoever among you sees an evil action, let him change it with his hand (by taking action); and if he cannot do that, then with his tongue (by speaking out); and if he cannot do that, then with his heart (by believing that it is wrong and hating it) – and that is the weakest of faith.” (Narrated by Muslim in his Saheeh from the hadeeth of Abu Sa’eed al-Khudri (may Allaah be pleased with him). If the interests of sharee’ah are better served by a person’s staying in the environment where the evil action is taking place, and they outweigh the negative outcomes, and he does not fear that he will be overcome by temptation if he stays among people who are committing this sin, and he also denounces it according to his means, (this is OK); otherwise, he should forsake them in order to protect his own commitment to religion.