Good on you for being brave to talk to your friends about Jesus. It is often tricky to share your faith, you become quite vulnerable before your friends. My approach to your situation is drawn from something I’ve been reading in the bible lately and thinking about.
Have a read of Acts 4… notice how bold Peter is… then look back at Luke 22:54-62. Something happened between these events that completely changed Peter… and it wasn’t necessarily hearing something over and over to convince him… when Peter made that speech he was in jail for his belief! Surely normally he would be second-guessing himself at that point. But because of his conviction in Jesus - due to the work of the Holy Spirit - he was made bold, where before he had been a coward!
I wonder whether you have your own testimony that you could share - I know in my life there was a radical and very swift transformation. I was a very firm neo-pagan, practising witchcraft and harassing every Christian that I came across, then one night I heard the gospel and I knew that it was the truest thing I ever heard. It was never something ingrained in me, never something I was indoctrinated in… and there are lots of others like me!
When Peter was transformed, his knowledge of the Bible was the Old Testament, and his knowledge of the gospel was of seeing Jesus in person! He wasn’t indoctrinated or brainwashed - he was THERE! He was an observer! When I became a Christian I had almost no exposure to the Bible and certainly none to church… I wonder whether your friend has ever met anyone like that - who chose to become a Christian without any background… or whether she has ever read the Bible to see if she thinks it could be true…? You might like to ask. (Maybe you could give her a copy of ‘The Essential Jesus’ if your church has them - free copies of the gospel of Luke in easy-to-read English)
The important thing to remember for yourself (and to challenge your friend with) is that our belief in Jesus is based on hard solid historical evidence ... it is there to be read, studied and analyzed. If it is true it will always stand up to this kind of scrutiny so we should never be afraid to test what we believe. However most people who don’t believe have never looked at the evidence with an open enough mind and asked themselves “Who is Jesus?”. This is what I would challenge you to do with your friend. Maybe you could suggest that you meet together regularly and read a bit of a gospel. Let her ask questions and keep challenging her to consider who Jesus is.
These are just a few ideas. You will have a better idea of where you can go in your friendship, but hopefully this will help you think about some other things you could say.
I will pray that the Holy Spirit gives you the words to speak to your friend!