The emphasis of Huldrych Zwingli and John Calvin on the claim that forgiveness of sin is entirely a gracious (free) gift from God, and that humans can do nothing to cooperate with this gift, sets the Reformed narrative of salvation off from that of many other Christians.
Ultimate Reality and Divine Beings
Reformed Christians have a very strong doctrine of God's sovereignty. This doctrine is the cornerstone of Calvin's theology. Calvin also had a traditional view of Jesus as fully human and fully divine, and he believed in angels and the devil.
Human Nature and the Purpose of Existence
Humans were created in the image of God, but since the fall, human nature is sinful—fundamentally self-centered. The purpose of existence is to be in relationship with God, which is possible only through God's free forgiveness for sin.
Suffering and the Problem of Evil
Suffering is the result of evil, which is the result of sin. Responsibility for sin rests entirely on humans. We do not and cannot know why creation was set up in such a way as to allow for sin.
Afterlife and Salvation
Presbyterians, like most Christians, believe in a traditional idea of an immortal soul that will spend eternity either in a literal place of blessedness called heaven or a literal place of torment called hell. One's destination depends on whether or not one is saved, that is, by God's grace forgiven for sin.