How do we respond to the congratulations of Christians or non-Muslims in general on our holidays or various occasions when they say: "Kul 'am wa anta bi-khair" (May you be well every year) or "Mubarak 'alayk" (Blessed upon you)? And is it permissible for us to say to them: "Wa anta bi-khair" (And may you be well)?

A non-Muslim's greeting should be responded to with "And you be well" or "And you be in good حال (state/condition)." It is permissible to supplicate for their guidance and good health. Supplicating for worldly benefit for a non-combatant is also permissible. It is preferable to intend to supplicate for their guidance to Islam when responding to them, just as the Prophet, peace and blessings be upon him, used to say to the Jews when they sneezed: "May Allah guide you and rectify your affairs."