In Protestant Christianity, the relationship between Law and Gospel—God's Law and the Gospel of Jesus Christ—is a major topic in Lutheran and Reformed theology. In these religious traditions, the distinction between the doctrines of Law, which demands obedience to God's ethical will, and Gospel, which promises the forgiveness of sins in light of the person and work of Jesus Christ, is critical. Ministers use it as a hermeneutical principle of biblical interpretation and as a guiding principle in homiletics and pastoral care. It involves the supersession of the Old Covenant by the New Covenant and Christian theology.

Lutheranism is a major branch of Protestantism, identifying primarily with the theology of Martin Luther, the 16th-century German monk and reformer whose efforts to reform the theology and practices of the Catholic Church launched the Protestant Reformation.