All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
First of all, we praise Allaah who guided you and blessed you with the love of the Book of Allaah and the Sunnah of the Prophet, sallallaahu Sunnah 'alayhi wa sallam, and for making you steadfast on His Obedience. We ask Allaah to make you firm on His Religion until you die and enable you to guide other people to the truth, and comfort your eyes by guiding your family and relatives to the Straight Path.
Firstly, we advise you to fear Allaah and then continue to call your parents, family and relatives to Islam and not despair if they are not guided. You have the best example in the Prophets and Messengers of Allaah, may Allaah exalt thier mention. For example, the Prophet Nooh (Noah) continued to call his people to Allaah and did not despair for a period of 950 years, and when Allaah said to His Prophet Muhammad (what means): {Arise and warn.} [Quran 74:2], he called the people to Allaah without any despair for a period of more than twenty years until he died. Therefore, you should keep advising and calling them to Allaah as Allaah may guide them thanks to you, especially your parents because they have a great right on you more than any other person. In doing so, you should make use of beneficial books, tapes and every beneficial means. Also, you should endeavour to supplicate Allaah to open their hearts to Islam.
As regards what you should do when they commit sin either verbally or practically, then you are obliged to advise them. If they do not accept, then you should stand and leave because it is not permissible for you to sit with them if they say a forbidden speech or put intoxicants (alcohol) on their table because the Prophet said: “Whoever believes in Allaah and the Last Day should not sit at a table where intoxicants are served.” [At-Tirmithi]
Moreover, you are not permitted to help your parents in selling intoxicants or pork or other prohibitions because, if you do so, you are helping them in disobeying Allaah; Allaah Says (what means): {Help you one another in virtue, righteousness and piety but do not help one another in sin and transgression. And fear Allaah. Verily, Allaah is Severe in punishment.} [Quran 5:2]
For more benefit, please refer to Fataawa 90278, 83991, 87573 and 84743.
Allaah Knows best.