This change [alteration in method -DHC] revealed itself in (among other things) the following tendencies, which exerted a profound affect on the theology of the Enlightenment.
Theology came to be more or less dependent on philosophy and rational thought. Even in those presentations where the author did not wish to go so far as to replace revelation with natural religion, intending rather to stand fully within the Christian tradition, it was not uncommon to find rational arguments placed alongside revelation on an equal basis. The demand that reason be subjected to the testimony of Scripture was replaced by the firm belief that revelation and rational principles are in complete harmony, plus the desire to legitimize revelation in the presence of reason.
Parallel with theology’s rationalizing was its tendency to moralize. Morality is a more immediate concern than religion to the modern, rational view of life. The promotion of good morals was looked upon as Christianity’s main objective, and ethical content as its very essence.
The idea that religion was based in particular on principles inbedded in human reason supported an individualistic conception: religion became an individual, private matter, its certainty based on a person’s own experiences
A basic characteristic of the theology of the Enlightenment was the tendency to “humanize” Christianity, to accommodate it to an anthropocentric frame. Theology was expected to promote human welfare, and theological truth was expected to harmonize with commonly recognized rational principles. This-worldly goals predominated: earthly happiness and a rational morality were the primary benefits that men expected from religion.
(Bengt Hägglund, History of Theology, 339)
Many of these trends are still with us today, even in supposed "post-modern" circles.