I have a sister who has turned from Shi'a Islam to being a Salafi. She was influenced by one of her friends, who convinced her that Shiaism is not the right path. Despite trying my best to talk to her about this, she is not open to discussion about it. My father is upset about the situation too and he has also tried to talk to her, but she finds ways to avoid confrontation and even lies to him about her beliefs so that he does not question her further. We do understand that it is her choice to follow whatever religion she wishes to and we would never try to coerce her to change her beliefs but it is upsetting to see your family member stray from the right path.
Despite the fact that she jumps on every opportunity she has to ridicule my beliefs, I haven't said anything in return because there is no point in fighting over this. After over two years of being in this situation, I don't know what to do about it. My father also seems to have lost hope. The problem is that every time I have tried to start a rational discussion with her, she shuts me down by saying that I won't change my beliefs no matter what so why should I talk to her about any of this or that I'm only saying this because I'm a Shi'a, or she'll say something hurtful about my beliefs. It is clear that she hasn't really done any research, read any books or rationally thought about any of this- she just somehow got brainwashed into becoming a Salafi.
Do we, as her family members have a duty to try to guide her to the right path, or should we leave her to her ways? How can we talk to her or what can we do that will at least open some room for discussion?