Branch of Christian theology devoted to the intellectual defense of faith. In Protestantism, apologetics is distinguished from polemics, the defense of a particular sect. In Roman Catholicism, apologetics refers to the defense of the whole of Catholic teaching. Apologetics has traditionally argued positively to quell believers' doubts and negatively against opposing beliefs to remove obstacles to conversion. It attempts to take objections to Christianity seriously without giving ground to skepticism. Biblical apologetics defended Christianity as the culmination of Judaism, with Jesus as the Messiah. In the 2nd and 3rd centuries a number of Christian writers defended the faith against the criticisms of Greco-Roman culture, and in the 5th century St. Augustine wrote his monumental City of God as a response to further criticisms of Christianity following the sack of Rome in 410. John Calvin's natural theology attempted to establish religious truths by rational argument. The late 18th-century argument that a universe exhibiting design must have a designer continues to be used; apologists have also dealt with the challenges of Darwinism, Marxism, and psychoanalysis. See alsoApologist.