Jesus was fully God fully man. He has no sin. If you think Jesus got off scott free with his torturous payment,you may want to watch the "The passion of the Christ" which is a somewhat accurate depiction of his payment for us. Although, it is still not as it really was. Jesus went through a gruesome death . God did pay fully > in Jesus!
Which, btw, it appears to me that you want to place yourself on Gods level. I have already provided you scripture to do a study about that. God is God! He is the potter you are the clay. He is the creator and you are the creation. You have no right questioning why God does things. When you learn that you will fare better. You must have reverence. God is sovereign and God is just! He sets the bar;not you!
Its not like God is slipping in a surprise of damnation for the ones who reject Christ. He has made many a warning. Jesus spoke more on hell than he did heaven. His apostles spoke on hell as well while they may not have always said the word "hell",they did fairly warn just as God led them to do.
I hope I have answered your question for you............