Praise be to Allah.
Firstly, we praise Allah for having guided you to the truth, and we ask Him to make you steadfast and help you to attain all that is good. Remember that you have been greatly blessed, and if you devote your entire life and wealth for that purpose, that will be little in return for that blessing. Do you know how many millions of people of your father’s background worship rocks and human beings? Do you know that all these people believe that the Qur'aan is distorted and they regard the Sahaabah as kaafirs, apart from a few of them? Do you know that these people have revived the shirk of Jaahiliyyah and added more forms of shirk than were known in the past?
We do not call people to anything except worship of Allah, may He be exalted, and we also call people to venerate and respect the Prophet (blessings and peace of Allah be upon him) and not to impugn his honour or slander his Companions. As we love all of the Sahaabah and pray that Allah be pleased with them, and we seek to draw closer to Allah by loving them, we also love and respect the people of the Prophet's household (Ahl al-Bayt), and we seek to draw closer to Allah by loving them.
With regard to your dealings with your father, what we advise you is:
1.Be kind in your dealings with him as much as possible.
2.Strive to serve him as much as you are able, and do not spare any effort in doing so. Do not withhold any help or kind treatment from him.
3.Focus on your studies and do not let your neglect of them be a cause of you losing your religious commitment. What we understand from your message is that your father wants to take steps to prevent you from accessing our site and other beneficial Islamic sites because of your studies. So do not give him that excuse; study and progress in your studies; close the door to your father’s shaytaan so that he will not be able to make the issue of your studies a means of preventing you from following true guidance.
4.Do not make an open show of visiting useful Islamic websites in front of him, and do not make an open show of your following the path of Ahl al-Sunnah in front of him. Even more important is not arguing and debating with regard to good matters, because doing that openly may motivate him to prevent you from following the path of true guidance.
5.Pray for him and for all of your family to be guided to the right path. Strive to make this du’aa’ when you are prostrating and during the last third of the night.
6.Finally, we advise you to use wisdom in dealing with your father. If he teaches you to pray in the Shi’i manner and you cannot reject it, then accept it from him and pretend to agree with him, but pray in the manner established in the sound Sunnah. With regard to the way the prayer is done, the matter is broad in scope in sha Allah, and you come under the heading of one who is forced to do something. You are at an age when you are not old enough to separate from him, so be patient until the time comes when you can leave, then if Allah guides your father before that, you can stay with them, or you can leave and live independently, so as to protect your religious commitment.
And Allah knows best.