What should the only Muslim son in his Hindu family do when asked to cremate his parents' bodies, and how should he deal with his disbelieving family after converting to Islam?

We congratulate the brother on his embrace of Islam. A Muslim should treat his non-Muslim family kindly, for that might be a reason for them to embrace Islam. He must be dutiful to his parents and maintain kinship ties, without love, flattery, or obedience in disobedience to Allah, as Allah the Almighty says: "But if they endeavor to make you associate with Me that of which you have no knowledge, do not obey them, but accompany them in [this] world with appropriate kindness." If one of his parents dies and there is no one else to bury them, it is permissible for him to bury them to conceal them from people, based on the hadith of Ali, may Allah be pleased with him, with the Prophet, peace and blessings be upon him, regarding Abu Talib. However, if they insist on cremating the deceased, it is not permissible for the Muslim to participate in that, due to its contradiction with their religion and because it involves humiliation of human dignity.