Is it permissible for a Muslim woman to greet her adult Christian maternal brother by kissing and embracing him, and to uncover her head and greet her Christian female colleagues by hand or by kissing, and how should she treat her Christian mother?

It is permissible for a woman to greet her disbelieving brother and treat him like any other unmarriageable kin (mahram), because the difference in religion does not prevent mahramiyyah according to the majority of scholars. They cite the verse: "And not to show their adornment except to their husbands, or their fathers, or their husbands' fathers, or their sons, or their husbands' sons, or their brothers." Some scholars, however, are of the opinion that it is forbidden for him to travel with her without looking at her, citing the action of Umm Habibah with her father, Abu Sufyan. A woman must adhere to the Sharia limits in dealing with mahrams to avoid temptation. Furthermore, honoring one's parents includes a Christian mother.