Salaam o 'alykum warahmatulahi wabarakatuh.
sister, i think it depends on whose funeral it is. eg. a family members funeral may have a different opinion rather than of a non muslim whos not related to you, but Allaah subhanahu wa ta'aala knows best.
Dear scholars, As-Salamu `alaykum. Is it permissible for a Muslim to attend the funeral of his non-Muslim parents or relatives? Jazakum Allah khayran.
Wa `alaykum As-Salamu wa Rahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Dear sister in Islam, we would like to thank you for the great confidence you place in us, and we implore Allah Almighty to help us serve His cause and render our work for His Sake.
It goes without saying that Islam does not aim at severing the ties of kinship between its adherents and their non-Muslim relatives. Islam considers this relationship highly, particularly that between parents and their children. Islam does not reject or disregard such instinctive relationship.
Islam calls upon Muslims to be dutiful to and behave kindly towards their non-Muslim parents, no matter what their religion or lack thereof. Moreover, dutifulness to parents extends beyond their death and continues as long as we live. Hence, a Muslim is allowed and recommended to attend the funeral of his non-Muslim parents and relatives provided that he/she does not participate in any of the religious rituals.
In response to the question you raised, the European Council for Fatwa and Research issued the following Fatwa:
"Islam orders that parents be treated kindly and graciously even if they are non-Muslims. Almighty Allah says: “Your Lord has decreed that you worship Him and that you be kind to parents…”
(Al-Isra': 23) Allah Almighty also says: “Consort with them in the world kindly…”
(Luqman: 15) Islam also exhorts people to observe and maintain good relationship with kith and kin.
Moreover, Islam calls for respecting any person, whether a believer or a disbeliever, in his/her lifetime and posthumously. It is reported by Al-Bukhari and Muslim in an authentic hadith that the Prophet (peace and blessings be upon him) stood up when a Jewish funeral proceeded in front of him. Somebody informed him that the dead person was a Jew. The Prophet sal Allaahu alayhi waSalam replied: “Is it not a soul?”
Now, the soul of a father, a mother or a close relative is entitled to more respect. Therefore, a Muslim may attend the funeral of his non-Muslim parents or one of his non-Muslim relatives. He may attend the religious ceremonies held for the deceased in churches and synagogues, provided that he does not participate in the prayers, rites and other religious activities. He may also attend the burial. In all that, his intention should be to do the duty of kindness (to parents) and good relationship with kith and kin, and sharing the misfortune with the family and strengthening the relationship with relatives, and avoiding what may lead to estrangement if he fails to attend such occasions."
Excerpted, with slight modifications, from: http://www.ecfr.org
Dr. Salah Sultan, President of the Islamic American University and Professor of Islamic Jurisprudence, Cairo University, adds:
"A Muslim should attend the funeral of his non-Muslim parents just as a courteous gesture without participating in any of their rituals, for Islam has set certain rituals to be performed in funeral service; this leaves no room for any innovations. By attending, one shows that Islam is keen on maintaining relations. Allah Almighty says: " But if they strive with thee to make thee ascribe unto Me as partner that of which thou hast no knowledge, then obey them not. Consort with them in the world kindly…"
Birr (doing good) is a right a Muslim owes a fellow Muslim and non-Muslim as well. If it's a duty for a man to sustain his non-Muslim parents, then it is his responsibility to attend their funeral prayer and accept people's condolences as a righteous deed towards parents."
Allah Almighty knows best.
wa Salaam o 'alykum warahmatulahi wabarakatuh.