Is it possible for someone to have a good understanding of theology and the bible and not truly be born-again?
Oh yes, it is quite possible. There once was a Pastor who had been shepherding his flock a number of years. Had all the schooling, read the bible, even prayed a lot; still, he didn't understand what it meant to have a living relationship with Jesus Christ (although he thought he did), til one day.....well, that's another story.
On the other hand, your friend may indeed be
saved if she's ever taken the steps. But in order to have growth in our relationship with Christ, one must be obedient to his Word, and allow HIM to work in our lives. So, accepting Christ is our first step, but if you let it stop with that acceptance you will never find the riches he has stored away for us, one of those being "the peace that surpasses all understanding".
Pray for your friend! And while you are doing that, be a friend. When she'll listen, teach her what you know to be true.
may his peace fall upon you
Gracey