Prufrock, your situation remind me a little bit of the one I had with my dad when I was growing up, so I’ll share that long story that I’ve mentioned before.
My dad was the son of a Methodist preacher, and like a lot of preacher’s sons, got disillusioned. He eventually rolled his own version of Pantheism. I was brought up Presbyterian, not because I needed to be a Christian but because I needed to “have the influence of the Western European Judeo-Christian tradition” (my dad is a full-of-it intellectual).
At 18, I became a born-again Christian. A year later, I became a “Charismatic” (aka “Holy Roller”) Christian. My dad was apoplectic. To him, Christianity in and of itself was meaningless, and I was under the influence of mob mentality. We had more unpleasant mealtime religious debates than I can remember. We eventually had to declare an uneasy truce.
As a fairly intelligent, critical-thinking person with left-leaning politics, I never fit in easily with Christian faith-before-intellect right-wingers, but I was able tolerate the pig-headed ignoramouses (that wanted to run other people’s lives) that I went to church with.
Eventually I got involved in a Christian cult (part of the “Sheparding” movement) that was into controlling people’s personal lives (although I didn’t know it at the time). That’s where I met my wife. As things got wierder and wierder, we made the decision to get out. We engaged and married not long after that, and lived for many years without any kind of religious observance (we had such a sour taste in our mouths from the situation).
Now my wife came from a non-observant Jewish family who occasionally went to a Conservative congregation. My father-in-law once commented to my sister-in-law (upon her becoming a “Messianic Jew” (don’t yell at me, her term)) “Christianity! Judaism! It’s all crap! But Judaism is our crap!” When she became a Christian, it was always felt unnatural for her, and she was constantly struggling with doubt and very unhappy with it.
So after my wife and I had been married and not observing any kind of religion she was glad to not be going to church, and I still had such a sour taste in my mouth that I didn’t press the issue. Eventually she was drawn back to Judaism, began counselling with a Reform rabbi, and took a “Basic Judaism” class with a Conservative rabbi.
She decided to return to Judaism, and we decided to bring our children up as Jews, while I continue to remain Christian. By the way, coming from a Protestant heritage, I am quite comfortable with the concept of personal interpretation, hence that’s why Reform is the best fit for me culturally.
My children are being brought up in a strongly Jewish household, and so my parents have had to reconcile themselves with the fact that we don’t celebrate Christmas or Easter with them. My dad has attended Selichot service with me, and sends up holiday greetings on the various Jewish Holidays.
My point in this long story is that both my wife and I took a long, convoluted journey, but turned out OK. It may not have been what our families thought they wanted, but we’re OK nonetheless. All the yelling and consternation of our families didn’t factor into this result, it was us using our own good minds, our sense of self-esteem, and the guiding hand of G-d that got us here. If your sister has those things, she’ll do fine in the long run.