He ineffectually resisted the efforts of the Calvinists, led by Caspar Olevianus, to introduce the Presbyterian polity and discipline, which were established at Heidelberg in 1570, on the Genevan model.

This same Elector Frederick invited two young divines, Zacharias Ursinus and Caspar Olevianus,, to prepare the afterwards celebrated Heidelberg catechism, which in 1563 superseded Calvin's catechism in the Palatinate.

The Reformed churches of the Palatinate, on the other hand, used the Heidelberg Catechism (1562-1563), "sweetspirited, experiential, clear, moderate and happily-phrased," mainly the work of two of Calvin's younger disciples, Kaspar Olevianus and Zacharias Ursinus.