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, sallallaahu ‘alayhi wa sallam, is His slave and messenger.
We advise you to continue advising your relative by using various means to guide him and persuade him to give up what he is doing.
Moreover, you should know that those who call to Allaah should never despair because people’s hearts are controlled by Allaah, The Merciful, and He can easily change them as the Prophet, sallallaahu ‘alayhi wa sallam, told us. [Muslim]
Thus, you have to continue advising him and endure what he does or says to you and Allaah The Almighty would reward you for your patience.
Allaah Knows best.