The sixteenth- and seventeenth-century Reformed churches produced several families of orthodox confessions that promoted the Calvinist faith and differentiated it from Roman Catholicism and other groups of Protestant churches. The most well-known of these groups of confessions were the Swiss-Hungarian family, represented by the First and Second Helvetic Confessions (1536 and 1566) and the Helvetic Consensus Formula (1675); the Scottish-English family, represented by the Scots Confession (1560), the Thirty-nine Articles (1563), the Westminster Confession of Faith (1647), and the Shorter (1648) and Larger (1648) Catechisms of the Westminster Assembly; and the Dutch-German family, represented by the Three Forms of Unity: the Belgic Confession of Faith (1561), the Heidelberg Catechism (1563), and the Canons of Dort (1618-1619). Of those Reformed confessions, the seven most diligently adhered to by various Reformed denominations today are the Three Forms of Unity, the Second Helvetic Confession, and the Westminster Confession and Catechisms. They can be called “living” doctrinal standards because they are sanctioned officially by numerous twenty-first century Reformed churches. . .

One cannot avoid being amazed at the remarkable unity of Calvinist theology in the sixteenth and seventeenth centuries.

Joel R. Beeke, Living for God’s Glory: An Introduction to Calvinism , Loc. 384,498.