Is it permissible to remain in a marriage to a man who believes it is permissible to rule by other than what Allah has revealed, and who accepts what is forbidden, despite his knowledge of Allah's law, based on the principle of "There is no obedience to a creature in disobedience to the Creator" and verse 31 from Surat At-Tawbah?

Ruling by other than what Allah has revealed is impermissible. Believing that it is permissible, or that no alternative to it is satisfactory, is an act of disbelief (kufr). The one who holds this belief will not benefit from claiming that Allah's law is better and superior. If this is combined with consuming unlawful earnings, then it is a misfortune upon a misfortune. These people must be advised and the truth made clear to them. They should not be judged as disbelievers without careful consideration, because declaring a specific individual to be a disbeliever requires the fulfillment of conditions and the absence of impediments. If the husband is free from these matters, then praise be to Allah. If he is like them and there is no hope of his rectification, then efforts must be made to separate from him. It is not permissible for the wife to consume from her husband's wealth if his earnings are unlawful, except out of necessity and to the extent of that necessity. If his wealth is mixed, partly lawful and partly unlawful, then consuming from it is disliked but not forbidden.