I think every time I read this passage it gets deeper and deeper . Jesus says that we cannot see the kingdom of heaven unless we are born again, then He says "that which is flesh is flesh and that which is spirit is spirit. We must be born again because we are of flesh and we must be of the spirit to go to heaven . In Romans 8:5-8 , Paul explains further that no flesh can please God so God has to do something to us before we can be saved and that is found in John 6:44-Give this message a listen and let me know what you think.