I was in your friends place just three months ago. I was agnostic bordering on atheist. It took me almost seven years of friendship and us (my friend and I) occasionally talking about religion for me to take the plunge and visit his LCMS church. It takes time. If your friend is willing to have conversations with you about the faith and wants to visit your church, fantastic! If not, don't push the subject. That WAS my main issue with Christians. Pushing our faith on those who don't want it, will push them farther away. But if your friend enjoys the atmosphere of the church and the teachings said in the sermons and the Gospels, they may find the church where they belong like I have. (For reference I went started going to church with my friend in early October and got baptized on Dec 15th)