I know many Christians have been waiting for this manual. I am glad to share with you what I found.
Say something, anything, to your atheist friends and family members. Tell them that God loves them and that you’re praying for them if that’s all the time and courage you have. Share the gospel with them. Pray for them. Pray for them some more. But say something. You have no way of knowing how the Holy Spirit might use even the smallest act of love to break a sinner’s heart and bring them to repentance and faith.
I hope it works for you 🙂