Is it permissible to remain with a husband who does not pray and does not believe in Allah, in hopes that Allah may guide him, or is it obligatory to seek a divorce despite the parents' rejection, for the sake of the two daughters?

As long as the husband admits to his disbelief, he is considered a disbeliever by consensus. It is not permissible to remain with him, based on the words of Allah Almighty: "Then if you ascertain that they are believers, do not return them to the disbelievers; they are not lawful [as wives] for them, nor are they lawful [as husbands] for them." And the family's statement, "Perhaps Allah will guide him," does not permit remaining with him. Rather, it is obligatory to separate from him. If he embraces Islam before the end of her waiting period (iddah), then he remains her husband; otherwise, there is no return.