Assalammu Alaikum shaykh I know someone who's family is entirely deobandi, they oppose salafiyaah a lot. That person is still under his family's gurdianship, how should he treat this matter? I am hiding the fact he is no longer a deobandi anymore. Is it fine to lie if was ever asked about it?

Hide it and do not do something that would harm you. Be patient. These are ibtilaat—trials, tribulations, and tests from Allah—so that you become patient, to show Allah patience from you and the strength of your religion. These things shape your piety, religiosity, character, and strength, as well as your willpower. So, Alhamdulillah, Alhamdulillah. You never know; this person can be a means or a reason why his family later on would enter into Salafiyya by the will of Allah.