What is the meaning of "Al-Musana'ah" (deference/conciliatory behavior) in Islamic law, and when is it permissible? Is smiling at a person who mocks the religion, in order to avert their evil and harm to people, considered permissible "Musana'ah"?

"Al-Musana'ah" (deference/courtesy) is applied to both "Mudaraah" (conciliatory behavior) and "Mudahanah" (compromising one's principles). "Mudaraah" is permissible, and it involves being gentle with others to extract truth from them or to dissuade them from falsehood. "Mudahanah" is forbidden, and it involves being gentle with others to affirm them in their falsehood. Smiling at someone who mocks religion is permissible if it is to ward off their evil and harm, without affirming their actions. However, if it is done in a way that affirms falsehood and follows whims, then it is forbidden.