Reinhold Niebuhr's concept of ideology, a synthesis of the doctrine of sin and sociology of knowledge, denotes any claim to absolute truth with reilsvested interests. Tolerance, its anonym, is based on an acknowledgement of one's own fallibity and need for forgiveness. Niebuhr thus intertwines Luther's two »realms«, without mixing them up. His theory is deemed a major contribution to both theology and political science.