“What, then, is necessary for a Christian to believe?” asks the Heidelberg Catechism. “All that is promised us in the gospel, which the articles of our catholic, undoubted Christian faith teach us in summary,” is the reply. Though this creed was not penned by the Apostles, it summarizes the Bible’s teaching with simplicity, brevity, and beauty. Originally used as a baptismal formula in the second century, it reached its present form in the sixth. It gives a concise expression of the fundamentals of historic Christianity.