You'll have to make the choice what is more important to you: you being able to buy a book or her recovery (I can't be sure that that is the situation, but it seems to be how you are describing it).
Do what you think is right. Nobody can judge the situation better than you can.
Thanks Matt, maybe I should get another book instead
She's pretty much recovered but I think I phrased it wrong, telling her how religion is poisonous and belief in god is irrational might make her think differently and affect her negatively. That's why I have this dilemma.
I've only come out of the closet to my close family. To the rest (granny cousins uncles etc) I haven't, mostly because I am only half-fluent with spanish and won't be able to express my view clearly, and because I don't want it to affect our relationship (especially grandma, she's very religious)
I think it's a dilemma many atheists face, especially those in religious countries. I didn't have a similar experience, but I can emphatize.
Look, my perspective is this:
We need more people in the world to combat bad ideas, and one set of bad ideas is religion. So we would benefit from having more 'out' atheists to do this, both to have people planting those seeds of doubt and promoting rationality in general, but also to show their family and the people around them that atheists are just regular folks.
However, it doesn't have to be you. It's a choice, not a duty. In some situations being an out atheist just isn't smart: you can become a social outcast, your family can abandon you and in some countries you can actually find yourself in physical danger.
This is true especially for young people: odds are you'll be financially reliant on your parents for up to a decade, and so if coming out or publicly criticizing religion is going to be really controversial, you're risking your education and much more.
Then there's the emotional side of things. While it's true that your beliefs are ultimately your business and that you get to say what you want, if it is really going to hurt the people you love, you might still decide against it.
On the bright side, I do remind people that even if they conclude that they are not in a situation to safely expose religion as a bad idea, there's plenty of other domains where we need more rationality -politics, economics, morality, the paranormal in general... Promoting rationality is ultimately what we need: what area doesn't really matter and is up to you.
And again, I can't tell you what your situation is or what course of action you should or should not take, I'm just giving you my perspective and perhaps you'll find some of it valuable. Don't let someone on the Internet decide how you should live your life. In the end it's your call ;)
Torkoal again i can sympathize with you, my Spanish is also not that great, i find that defending my Atheism or any philosophical position i hold in Spanish to be quite tedious and bothersome, i feel that my family just doesn't understand me, that is partly due to the language barrier between us.
I chose a path of being open about what i believe but i am surely not in the same situation as you and that is indeed important to keep in mind. I agree with Matt in that at the end of the day it is your choice. You should take much care in making it. I am only speaking for myself when i say i am glad i came out of the closet as an Atheist to them. I for one have a strong support base that is my closest of friends who happen to be either atheists or agnostics or just secular in some form. I should also mention that ever since i started being public about it i have noticed some of my younger U.S. born family members to get into questioning the existence of God with me and it seems that i have become slightly influential in being a sort of godless Socratic gadfly.
Again i have to stress that i am in a different situation from you, think carefully about it and definitely take others into consideration. Out the closet atheism isn't for everyone.
Dan Barker Bio link
My only problem with Barker is that he seems to have a hard time distinguishing between good arguments against religion and bad arguments.
The way he swiftly jumped on the Jesus Mythicist bandwagon for instance, makes me think he'll support just about anything that's anti-religious.
I think it is so sad, when a person like you, Torkoal, has to live a lie, or hide the truth, or tolerate nonsense from others, for the sake of those others. I guess it goes to show that atheists aren't evil, when they keep their ideas under wraps, for the sake of family members who would be hurt by the exposure of said ideas. But what of the hurt and stress that is caused to the atheist, in living like that?
Being atheist isn't necessarily easy !