I wouldn’t go. That would be tacit approval of a sinful act. It would show you somehow approve of what she’s doing. Let her know that you love her, but cannot, in good conscience attend, and she knows why. She’s taking someone’s personal interpretation of Scripture over the interpretation of the Apostles and their successors, the bishops. Ask her why, if personal interpretation is so great, that there are tens of thousands of denominations? (And, yes, the non-denominationals are a denomination. Who are they trying to fool? Like saying the uncola cola. Funny, but sad.)
With regard to the Rosary, she probably doesn’t know that it is the prayer of the Gospel. All the prayers and mysteries come from the Bible. We meditate on the mysteries. It was how simple people learned the Gospels before universal literacy, which only began a little over 100 years ago.
History has shown that if one was Christian for the first 1000 years of Christianity, one was Catholic, since there was nothing else. In 1054, the Orthodox split off. Only in 1517 A.D. did Protestantism get its start, and it has been splintering ever since into literally tens of thousands of man-made, doctrinally disagreeing denominations. The Catholic Church is different in essence from all those who splintered off in that it is not just a mere organization. It is a Divine organism, with Christ as its head, and the Holy Spirit as its spirit. The Catholic Church alone has the fullness of Christ’s truth, and the fullness of the tools of salvation given mankind. If she wants better fellowship, then tell her to join the Elk’s Club or something. If she truly wants to bring people to Jesus, there is no better way than to bring them to Him in the Eucharist, where He is present, His Body, Blood, Soul, and Divinity! She won’t find that in a non-denominational denomination. Not even close. She’s traded the Mystical Body of Christ for back-slapping, hand-shaking, feel-good fellowship and erroneous personal interpretation of Scripture.
If we all pray for her, maybe she’ll come way back the right way and find a vocation to the religious life! If she wants to really serve Christ and bring people to Him, then she could dedicate her whole life to Him. Here’s some videos that might pique her interest:
youtu.be/uFFiNRvXBQw
youtu.be/UDcC5NaKnAY
youtu.be/sW8A9uvSjSg
I have a first cousin who’s a Dominican nun there. They are all glowing with happiness, holiness, and serenity. Heaven on earth! I’ve never seen that many women so happy. (I was there for three days when she took her final vows!) Never saw one frown. Ever.