What is the ruling on showing courtesy to an opponent or a person who commits a reprehensible act, with the intention of influencing them, winning their heart, and guiding them back to righteousness, such as saying "You are right" or "You are correct" while not inwardly agreeing, and does this fall under the category of engaging in unproductive discussions with them and dealing with them according to their level of understanding?

The fundamental principle regarding enjoining good and forbidding evil is their obligation. However, forbidding evil may be abandoned if it leads to a predominant harm or a greater evil. It is permissible to delay enjoining good and forbidding evil if the benefit of delaying outweighs the immediate action, such as when the person being called to good is more likely to respond at a later time. This falls under the wisdom of da'wah (inviting to Islam), as exemplified by the Prophet, peace and blessings be upon him, in his gradual prohibition of alcohol. So, if you see that delaying the call is more beneficial, there is no harm in that. The important thing is to adhere to this guideline: that silence does not lead to agreement with or endorsement of the evil, and that courtesies are extended for the purpose of gentleness and reforming the one being called, not for worldly gain.