What should a Muslim say to a non-Muslim relative when they say to him, "I love you," and is it permissible for the Muslim to say to him, "I love you too"?

The submission of one's heart and face to Allah requires that love and hatred be for His sake, as the Prophet, peace and blessings be upon him, said: "Indeed, the firmest handhold of faith is to love for Allah and to hate for Allah."

However, this does not preclude the existence of an innate love between a Muslim and a disbeliever due to kinship, lineage, or kindness, such as the love of the Prophet, peace and blessings be upon him, for his uncle Abu Talib, or a husband's love for his Kitābī (People of the Book) wife. This love is natural and instinctive, and it does not contradict disavowal of the disbeliever's religion and enmity towards them in that regard.

A distinction is made between loving a disbeliever for their religion, which is an act of disbelief, and loving them for worldly reasons or kinship, which is permissible and does not contradict hating them in religion and disavowing their disbelief.