Is it permissible to give a gift to a Christian doctor who works diligently in a public hospital, knowing that the gift is not intended as a bribe, but rather as a reward for him, and in hope that it will be a reason for him to be drawn to Islam?

Scholars have differentiated between a gift (hadiyah) and a bribe (rishwah). The forbidden gift is that which is given to invalidate a right or establish a falsehood. This is among the major sins, and the Prophet, peace and blessings be upon him, cursed its doer. As for the commendable gift, it is that which fosters closeness between people, such as giving a gift to a man in appreciation of his efforts and to encourage him towards Islam. There is no harm in this; rather, it may bring reward and win over his heart.