What is the ruling of Islamic law regarding a young man's isolation from his parents who do not pray, and what is incumbent upon him to do towards them, especially after his repeated, yet fruitless, attempts to advise them, and his being forbidden from being harsh with them?

Prayer is the pillar of faith, and abandoning it demolishes faith. A Muslim is not permitted to abandon it for any reason, and family members should be taught its importance. Gentleness, kindness, and wisdom are recommended in inviting others to prayer, especially with parents, and one should not be harsh with them. Among the best ways to advise parents are: honoring them and showing them kindness, utilizing appropriate opportunities for advice, seeking assistance from those who influence them, avoiding embarrassing them or hurting their feelings, and supplicating for their guidance, for guidance is in the hand of Allah.