How should a Muslim deal with his kaafir family?

Praise be to Allah.

The one whom Allah has guided to Islam must hasten to convey this light to his family and relatives, because they are the first people whom he should call and to whom he should bring the light of Islam. If there are among them people who do not object to Islam, then this is a great blessing which the Muslim should make the most of to present Islam to them in the best manner. He may use any permissible means to call them to Islam, such as giving them audio and video tapes, books and websites, inviting influential Muslim people, drawing close to them by means of gifts, treating them kindly and good attitudes. He should avoid being harsh in his approach and he should always pray to Allah to guide them. 

As Allah has enjoined treating parents with kindness even if they call their child to kufr and strive hard in doing so, then it is more appropriate that this kind treatment be extended to those who approve of your being Muslim and do not object to it. Allah says:

{وَوَصَّيْنَا ٱلْإِنسَـٰنَ بِوَ‌ ٰلِدَيْهِ حَمَلَتْهُ أُمُّهُۥ وَهْنًا عَلَىٰ وَهْنٍۢ وَفِصَـٰلُهُۥ فِى عَامَيْنِ أَنِ ٱشْكُرْ لِى وَلِوَ‌ ٰلِدَيْكَ إِلَىَّ ٱلْمَصِيرُ . وَإِن جَـٰهَدَاكَ عَلَىٰٓ أَن تُشْرِكَ بِى مَا لَيْسَ لَكَ بِهِۦ عِلْمٌۭ فَلَا تُطِعْهُمَا ۖ وَصَاحِبْهُمَا فِى ٱلدُّنْيَا مَعْرُوفًۭا ۖ وَٱتَّبِعْ سَبِيلَ مَنْ أَنَابَ إِلَىَّ ۚ ثُمَّ إِلَىَّ مَرْجِعُكُمْ فَأُنَبِّئُكُم بِمَا كُنتُمْ تَعْمَلُونَ}

'Translation' {And We have enjoined on man (to be dutiful and good) to his parents. His mother bore him in weakness and hardship upon weakness and hardship, and his weaning is in two years- give thanks to Me and to your parents. Unto Me is the final destination. But if they (both) strive with you to make you join in worship with Me others that of which you have no knowledge, then obey them not; but behave with them in the world kindly, and follow the path of him who turns to Me in repentance and in obedience} [Luqmaan:14-15]. 

Ibn Jareer al-Tabari (may Allah have mercy on him) said: "[This means:] And if your parents strive with you to make you join in worship of Me anyone alongside Me, when you know that I have no partner -for He has no partner, exalted be He far above that- then do not obey them in what they want you to associate with Me {but behave with them in the world kindly} and obey them in that which has nothing to do with the relationship between you and your Lord, and does not involve sin" (Tafseer al-Tabari [10/139]). 

Ibn Katheer (may Allah have mercy on him) said: "i.e., if they strive hard to make you follow them in their religion, then do not accept that from them, but do not let that prevent you from keeping good company with them in this world, i.e., by being kind to them. {and follow the path of him who turns to Me in repentance and in obedience} means: the path of the believers." (End quote, Tafseer Ibn Katheer ([6/337]). 

The scholars of the Standing Committee for Issuing Fatwas were asked: 

I have family who are mushrikeen (polytheists) except one sister who is a Muslim. Is it permissible for me to live and eat and drink with them, and if that is permissible so long as it is not at the expense of my religious commitment, then it is permissible for me to tell them frankly that they are kaafirs who are outside of the religion of Allah? I have called them to Islam but they are hesitant, and they do not belong to this group or that, although they are closer to shirk, and I cannot find anywhere to live except with them. 

They replied: 

What you must do is continue to advise them, remind them, keep good company with them, and speak gently to them. If you are wealthy, then spend on them, in the hope that Allah may open their hearts and show them the light. Allah says:

{وَإِن جَـٰهَدَاكَ عَلَىٰٓ أَن تُشْرِكَ بِى مَا لَيْسَ لَكَ بِهِۦ عِلْمٌۭ فَلَا تُطِعْهُمَا ۖ وَصَاحِبْهُمَا فِى ٱلدُّنْيَا مَعْرُوفًۭا ۖ وَٱتَّبِعْ سَبِيلَ مَنْ أَنَابَ إِلَىَّ ۚ ثُمَّ إِلَىَّ مَرْجِعُكُمْ فَأُنَبِّئُكُم بِمَا كُنتُمْ تَعْمَلُونَ}

'Translation' {But if they (both) strive with you to make you join in worship with Me others that of which you have no knowledge, then obey them not; but behave with them in the world kindly, and follow the path of him who turns to Me in repentance and in obedience}[Luqmaan:15]. 

Look for various means of conveying the truth to them, such as letters, books and tapes (End quote, Shaykh 'Abd al-'Azeez ibn Baaz, Shaykh 'Abd al-Razzaaq 'Afeefi, Shaykh 'Abd-Allah ibn Ghadyaan, Fataawa al-Lajnah al-Daa'imah [12/255-256]).  

Shaykh Saalih ibn Fawzaan al-Fawzaan (may Allah preserve him) said:  "Allah has enjoined kindness to parents even if they are kaafirs. He says :

{وَوَصَّيْنَا ٱلْإِنسَـٰنَ بِوَ‌ ٰلِدَيْهِ حَمَلَتْهُ أُمُّهُۥ وَهْنًا عَلَىٰ وَهْنٍۢ وَفِصَـٰلُهُۥ فِى عَامَيْنِ أَنِ ٱشْكُرْ لِى وَلِوَ‌ ٰلِدَيْكَ إِلَىَّ ٱلْمَصِيرُ . وَإِن جَـٰهَدَاكَ عَلَىٰٓ أَن تُشْرِكَ بِى مَا لَيْسَ لَكَ بِهِۦ عِلْمٌۭ فَلَا تُطِعْهُمَا ۖ وَصَاحِبْهُمَا فِى ٱلدُّنْيَا مَعْرُوفًۭا ۖ وَٱتَّبِعْ سَبِيلَ مَنْ أَنَابَ إِلَىَّ ۚ ثُمَّ إِلَىَّ مَرْجِعُكُمْ فَأُنَبِّئُكُم بِمَا كُنتُمْ تَعْمَلُونَ} 

'Translation' {And We have enjoined on man (to be dutiful and good) to his parents. His mother bore him in weakness and hardship upon weakness and hardship, and his weaning is in two years- give thanks to Me and to your parents. Unto Me is the final destination. But if they (both) strive with you to make you join in worship with Me others that of which you have no knowledge, then obey them not; but behave with them in the world kindly, and follow the path of him who turns to Me in repentance and in obedience} [Luqmaan:14-15]. 

So you must treat your secular parents kindly, but with regard to religious matters, you should follow the true religion even if it is different from your parents' religion, whilst also treating parents kindly in return for their good tretament. So you should treat them kindly and return their favours, even if they are kaafirs. There is no reason why you should not uphold ties with your father and honour him and return his favours, but do not obey him in any matter that involves disobedience towards Allah, may He be glorified and exalted (End quote, Al-Muntaqa min Fataawa al-Fawzaan [2/257], question no. [226]). 

And Allah knows best.