Would I be sinful or responsible if my health condition or actions caused my parents to waver in their faith, or caused my mother to resume cursing the religion?

Denouncing evil is not an excuse for raising one's voice at parents; rather, politeness and gentleness are required when doing so. One must apologize to the mother and repent sincerely to Allah for saying "shut up." Cursing religion is an act of disbelief, and the mother should be advised to abandon this ugly act, seeking help from those they trust. Every individual is responsible for themselves. Caution must be exercised to avoid causing discord between parents, especially through provocative actions, and one should continuously pray for their guidance.