Post tenebras lux. After darkness, light. It was the faithful cry of Job and no doubt many martyrs. It is the latin phrase that came to be the adopted motto of the protestant reformation. Scholars debate about when the reformation began as much as they debate its influence on modern society. While proto-reformers such as John Wycliffe and Jan Hus came before him, the birth of the reformation is retrospectively considered to be October 31, 1517. It is on this date that Martin Luther posted his Ninety-five Theses against the bondage of the church practice of indulgences. The Theses were merely the start as Luther would go on to argue the prime issue that would revive church: Justification by faith alone. The "alone" is key. In Romans 1:17, we read "The just shall live by faith." It was here that Martin Luther was awakened and saw the beauty of the Gospel. He understood that this justice or righteousness is "a righteousness that God gives freely by His grace to people who don't have righteousness of their own." Like the Philippian Jailer in Acts 16, Luther essentially asked himself the same question: "What must I do to be saved?" How can one be declared righteous by God by a righteousness that belongs to someone else? The answer is "Believe on the Lord Jesus Christ" for He alone is our righteousness. He alone is our savior. A massive wave of reformers would follow Martin Luther and change the world. Among these are Huldreich Zwingli, Martin Bucer, John Calvin, and John Knox. Men such as these would refine and carry the faith throughout Europe, into the new world, and beyond.
It is often said that the church needs to return to the New Testament church. What is meant is a return to Biblical Christianity. This is precisely what the reformers sought to do. While the reformed faith passionately affirms the ancient universal creeds of the church, it also produced some of the richest and most detailed creeds that the church has ever known such as the Three Forms of Unity (Belgic Confession, Canons of Dort, Heidelberg Catechism) and the Westminster Confession of Faith. It is in these documents that the only infallible rule of faith and practice, Holy Scripture, is so faithfully and brilliantly confessed.
Reformed theology is sometimes termed Pauline, sometimes Augustinian, and popularly Calvinist. While all of this is true enough, the great Pastor Theologian C.H. Spurgeon put it best when he said, "Reformed theology is nothing other than biblical Christianity."