How do I convince my brother to stop straying from Islam, and I mean severely straying. I have hidden all of the things he does from my parents, for sure for the best, but he's going out of control. He's picked up drinking, I don't know since when, he's extremely violent, towards my sisters, and even raises his hand to my father. My father threatens to phone the police, but I don't want the authorities to get involved into this. He seems to have lost all sense of faith, refuses to pray and keep fasts. I don't know how to talk to him anymore either, once again because of his violent attitude. All I've been able to do so far is protect my sisters from his abuse when I'm home (I'm living on campus right now). I know that Allaah guides whom He wishes, but there must be a way to get through to him. I'm sure he's been scarred, probably because of my family's days functionality, but I know also that he needs to revert back to a proper human being, he's very dangerous right now. He's working as a bouncer in a night club downtown, and I know it will be extremely hard to convince him to drop out of that job. Also his tough guy attitude only thickens as he keeps working there. Every time I go back home I can see how he's getting worse and worse, and I feel like its my fault for not helping him change or rather stop changing.
Please help and make Du'aa for my brother and my family, and myself. My brother is not an uneducated Muslim, he's been to Tabligh Jamaa't enough times, as well as myself, but he's grown very very distant over the years.

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. We ask Allaah to exalt his mention as well as that of his family and all his companions.

First we guide you to advise your brother and to remind him of Allaah and of the reward that He Has prepared for His obedient believers and remind him of the threat that Allaah promised to the disobedient sinful people. Remind him that death comes suddenly and that he will be questioned for every act. However, you have to be very patient in calling him to repent, and behave with him in a good manner to make him feel that you are merciful towards him and that you are keen on guiding him to the straight path. Behave with him in the manner a doctor behaves with a patient. Be kind to him and advise him gradually by choosing the appropriate occasions and using different ways, sometimes arousing his interests in Paradise and others by frightening him from the punishment of Hellfire. Seize the opportunity of incidents that might affect him and soften his heart, like the death of a relative and the like. Do not hasten for results, as being hasty to get results might cause you to despair and consequently lead you to giving up this task.

Seek the help of Allaah and invoke Him earnestly as He is the One who is able to guide him if He so wishes. Indeed our hearts are between the two Fingers of Allaah and He turns them as He wills. If the supplication is made by the parents then it is accepted and responded to, as the Prophet said: "There are three supplications that are answered without any doubt: The supplication of a victim of injustice, the supplication of a traveller, and the one of a father for his children." [Ibn Maajah]. However, if he does not take heed, persists in committing sins and your advice is of no avail, and you are sure that cutting relations with him would be beneficial, then there is no harm on you to do so, and this might even be an obligation on you. However, if you fear that cutting relations with him would lead to a greater harm, then it is more appropriate not to cut relations with him and continue to advise him and be patient towards him.

May Allaah increase your zeal to do good and enable you to be steadfast on the correct path and comfort your eyes by guiding you and your brother and all your family to the straight path. 

Allaah knows best.