How Humanism Entered the Church

At its core, therefore, the Reformation was the removing of the humanistic distortions which had entered the church.

It is worth reiterating the ways in which the infiltration by humanistic thought--growing over the years but fully developed by 1500--showed itself.  First, the authority of the church was made equal to the authority of the Bible.  Second, a strong element of human work was added to the work of Christ for salvation.  Third, after Thomas Aquinas there had come an increasing synthesis between biblical teaching and pagan thought.  This synthesis was not just a borrowing of words but actually of content.

Francis A. Schaeffer, How Should We Then Live?, p.82