Christ took the punishment , out of an act of love and mercy , so that humanity didn ' t have to . How can one person take another person ' s punishment ? If I ' m sentenced to prison for killing a man , can I send my son in my place ? Justice is when a person gets what they deserve if I deserve punishment , but my son willingly takes my punishment , how has justice been served ? God is absolutely fair and just . Everybody has to be held accountable for their sin , and God has given every human an opportunity to repent . But you said people deserve punishment for their sins . If some people don ' t get punished for their sins , where ' s the justice ? Geez , sometimes I wonder if atheists even have a basic understanding of Christian theology and beliefs . I guess not . This is Sunday school level stuff . Charming . I ' m well aware of what the religion teaches , thank you very much . The problem is that this version of Christian theology is internally inconsistent everyone deserves punishment , God is perfectly just , and yet people can get off Scott free if they accept a proxy .