Is it permissible to eat and drink at the home of a young Muslim man whose money comes from drug dealing, and is it permissible for him to donate to mosques?

It is not permissible to eat or drink from wealth known to be unlawful, for the Prophet, peace and blessings be upon him, said: "No one whose flesh has been nourished by unlawful means will enter Paradise," and "Every body that has been nourished by unlawful means, the Fire is more befitting for it." Donating unlawful money for building mosques and the like is a way of getting rid of it, and its owner will not be rewarded for it, because Allah is good and accepts only what is good.