What is the ruling on dealing with taxi passengers who commit various sins or whose earnings are unlawful, and on the money earned from them in these cases? And is the driver sinful if he is unable to object to someone who insults the religion?

He who is hired to transport a person to a permissible place incurs no sin in dealing with him or benefiting from the fare. He is not obligated to inquire into the passenger's beliefs, or his transgressions, or the source of his money, for the default presumption is that what is in a Muslim's possession belongs to him. However, if the passenger intends to commit a forbidden act in the car, such as reviling religion or drinking alcohol, the driver must prevent him and denounce it to the best of his ability. If he is unable, then with his heart, for the Prophet, peace and blessings be upon him, said: "Whoever among you sees an evil, let him change it with his hand; if he cannot, then with his tongue; if he cannot, then with his heart—and that is the weakest of faith."