What are the responsibilities of a Muslim towards his or her non-Muslim siblings and parent? Is he allowed to arrange the wedding of his non-Muslim sister if the parents are not alive? What if the wedding does not take place in a church, or there is no priest involved in the registration of the marriage? My other question is that a fellow Muslim sister has been placed in a school having a significant number of Christian teachers. She is supposed to teach mathematics and physics. Since it is very hard for her to make changes in the arrangements, and since the school luckily, accepted her participation even after discovering that she was a Muslim, it would be quite troublesome for her to dispense with this alternative. The question here is whether she should still proceed with the arrangements, or should she back out and find another option. In this kind of situation, is it wise for us Muslims to mingle with non-Muslims? This could prove to be a challenge for us to see how well we could maintain our imān and obligations amidst non-Muslims. After all, this is all in the quest for knowledge. But still, is it wise for us to do that?
The antagonistic behaviour Muslims have generally adopted towards non-Muslims is totally uncalled for. They should remember that hostility and confrontation cannot be shown to them by Muslims after the departure of the Prophet (sws) and his companions. The Almighty Himself, through the last Prophet (sws) and his companions, had unveiled the truth upon those of them who were present in those times. They had denied it even after being convinced of it. Therefore, they were punished for this arrogance. Today, we cannot be certain whether the truth has been completely unveiled to them in its ultimate form. So we Muslims cannot be antagonistic and hostile to them. We must try to be true preachers of our religion and, as a general principle, deal very affectionately with our non-Muslims relatives and colleagues. We must fulfil our obligations towards them both. Non-Muslim parents deserve equal respect as Muslim parents. Similarly, in the absence of parents, a Muslim brother should do all he can to arrange for his sister’s marriage whatever be her faith. In fact, in the absence of the parents, this is his obligation. He can certainly participate in the wedding ceremony even if it is taking place in the church. He may however avoid that part of the ceremony which is against his beliefs.
On this very basis, I have a similar reply to your second question: I think that the Muslim lady should stick to the job and remain among her Christian colleagues. She should try to develop friendly relations with them and whenever possible present the teachings of Islam to them through her deeds and words. Why should she back out? After all non-Muslims are human beings and if they have deviated from the right path, they should not be left alone there. As I said, Muslims must adopt a sympathetic attitude towards them and try to interact with them and bring them closer to Islam.