Now, I apologize for butting in if it's taken that way, but I would like to clarify what this person said, again if I'm butting in, I apologize in advance.
I believe this person was saying to leaves hints and have talks with subtle hints as to the truth of xianity. But, not to make your opinion/thoughts to strongly, but rather to let your sister was it? to think on her own. Allow her the room to grow, and realize it on her own, because she'll never forget the truth once known.
This could be one of the best methods I have ever read in response to a pisstianity class in school. Because, she'll have done it on her own, and taken her own power into her own hands. If she so chooses to leave xianity, then congrats. Although, I would try to be careful about the rest of your family(personal standpoint now)
Because if they find out you differ with what they follow, it may get ugly. It's still a while to go yet before our age is returned, so being secretive about whatever method you do would be best, even should you choose to not take mine, or the person's above. I wouldn't want you or your sister to get in trouble.
I would recommend remembering your sister's habits, and trying to work with those as in her tendencies, if you two can figure out ways to bond on the subject like say in an outing, or a talk as written above, and still educate her without getting in trouble yourself or her learning about your path, then that would be my personal opinion.
To answer your original question, there's no way Father Satan would ever be angry ever.
P.S. I tried to make this as understandable as possible. I hope i helped.
