It can take time, people only wake up when they are ready to and for some that can take a long time.
If you want to try and save her then you need to take the time to educate yourself about the cult and how cults work before you can begin to help her to see it for what it is.
There are plenty of experiences on here of couples and what worked and what didnt, one thing that doesn't work is shoving it down the throat of your mate and bombarding them with information. So slow and steady is the way and learn when to shut up and when to speak about it.
She will not see this in a weekend, if it's half hearted or against their will then they may still believe in it and return at a later time, they need to see it for themselves and they only do that when they are ready. You need to be ready first though.
Take your time and dont do anything rash is always the advice given.