"the father of existentialism

Kierkegaard has been called "the father of existentialism." Explain how Kierkegaard, who is a radical Christian, and Sartre, who is a radical atheist, can BOTH be called existentialists. Be sure to properly cite your sources in APA format. Order Description   Kierkegaard has been called "the father of existentialism." Explain In proper and complete ESSAY format how Kierkegaard, who is a radical Christian, and Sartre, who is a radical atheist, can BOTH be called existentialists. Be sure to properly cite your sources in APA format.