I don't get hell

I'm an atheist, so by definition I don't believe in heaven or hell, but I really don't get the concept of hell in the first place. The concept of hell makes no sense to me. Why would the Satan punish the evil? One would think he would reward anyone who rejects God or furthers his cause. It never made sense to me that if you are a Christian then you get eternal awards regardless of the type of person you were in life, but if you an atheist you suffer eternal damnation. It's a binary decision and silly. 

Do I suffer forever in hell that same way a murder would? Why would I suffer at all? Hell should be a party. 

A pastor once explained that being cast into hell was horrible because you were denied the presence of God. If hell is horrible because you don't get time with God, then what use is Satan and his torturous minions? None of it ever made sense. 

The most unbelievable aspect of heaven and hell was the prayer for forgiveness. Can you really commit horrible crimes and be admitted to heaven simply because you prayed your sin away? How simple is that? Son… I know you killed a man today, but if you confess your sin and get right with God, I'll see you one day in heaven. What use is hell if not to pushed the murders among us? 

Heaven and hell are concepts for children. I stopped believing in the concept as child. I'm never going back.