Well, #1. If they realized they were a sinner... Be honest with yourself and God. Agree with His Word. He already knows EVERYTHING about you! "For all have sinned and come short of the glory of God." Romans 3:23 (kjv) #2. Recognize your need for salvation... If you desire to go to Heaven when you die, you first must be saved-saved the Bible way. "For by grace are you saved through faith; and that not of yourselves: it is the gift of God; not of works lest any man should boast." Ephesians 2:8-9 #3. Repent of your sin... Be willing to turn from your and from your attempts to save yourself, and turn to Jesus Christ who is waiting to save you. Luke 13:3, John14:6 and #4. Receive Christ as personal Saviour... Pray this prayer: Lord I know I am a sinner and I ask you to forgive me of my sins and come into my heart and be my Saviour. Thank you for saving me... If an atheist hasn't done that once in their life then their going to Hell. And how to tell if you're saved is if God has ever convicted you of doing something wrong. If God hasn't dome that in the last month or two, you're not saved.