The heart of the Reformed theology is found in the three (or four) ‘sola’-statements: sola gratia, sola fide, sola scriptura and solus Christus. In the Middle Ages many such ‘sola’-statements were uttered, but with the Reformation they are antithetically deepened and they signal a contrast: salvation is not earned through works, authority in faith issues is not in tradition. At the Council of Trent (1545-1563) Rome chose a synthesis of statements: faith and works, Scripture and tradition, grace and merit.

The development of sola gratia is apparent in Luther’s explanation of the Epistle to the Romans from 1515-1516. In the years after he retrieved more and more from that letter the consequences ‘sola fide’. When he came into conflict with Rome about his discoveries, the question of authority was manifested. The debate with John Eck in Leipzig (1519) cleared Luther of the accusation that he wrongly set Scripture above tradition. In the aftermath of this and against the scepticism of Erasmus, he also learned and described the ‘clarity’ of Scripture (claritas scripturae).

The use of the triad ‘sola gratia, sola fide, sola scriptura’ as a summary of reformed theology is from a later date, just as is the distinction between sola scriptura as the formal and sola fide and sola gratia as the material principles.