Islam, as a universal religion, calls upon Muslims to be good and tolerant with people. The Islamic message is welfare to all humanity. Cooperation in goodness and justice is encouraged by Islam whether between Muslims, or Muslims and non-Muslims, particularly the People of the Book.
Allah, the Almighty, says in the Qur’an: “Allah forbiddeth you not those who warred not against you on account of religion and drove you not out from your homes, that ye should show them kindness and deal justly with them. Lo ! Allah loveth the just dealers.” (Al-Mumtahanah: 8)
This verse, and many others in the Qur’an, lay down the main basics in dealing with non-Muslims.
Therefore, it is permissible for a Muslim to attend the wedding or funeral of a non-Muslim with whom he has some kind of relationship.
Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states: “It is permissible to attend a Hindu wedding in a temple. To do so is often dictated by our duty of good neighborliness. Islam teaches us to be kind and charitable towards our neighbors and reciprocate kindness with kindness and peace with peace. This is regardless of whether we share their religious beliefs or practices. Moreover, there is nothing evil about marriage itself, even though it is performed in a temple or a church or synagogue. However, while attending such functions, we must not be compromising our own beliefs and practices. Therefore, we should not participate in their specific religious rituals or practices; we must also not partake of the meals immolated in the name of or served to their gods.
Just as we are allowed to attend their weddings, we are also allowed to attend their funerals. There is no difference here between a temple, church or synagogue. The bottom line is: We are allowed to attend these functions so long as we stay away from their specific religious rituals and practices.”