D. A. Carson, in Becoming Conversant with the Emerging Church, noted three periods of epistemology (the study “knowledge”), which I thought were helpful:
This is marked by the belief that all human knowledge is a subset of God’s knowledge. (Carson only considers Judeo-Christian epistemology.) The premodernist would start with God and work from there. Absolutist.
Has its roots in the 18th century Enlightenment. Its starting point is “I”, best expressed in Descartes’ famous statement, “I think, therefore I am.” For Descartes, this was the foundational statement of all human knowledge. The “I” (as I understand it) is the collective “I”, common to all human beings. From there, everything else was to be worked out, including the existence of God. The conclusions were to be true for all human beings. Marked by rationalism (use of logic and reason) and empiricism (observation and experimentation). Absolutist.
Moving on from Descartes, every “I” is unique. Each person must start with themselves. Everyone has a different perspective on what can be known. So what is true for me may not be true for you. Some see postmodernism as modernism gone to seed i.e. its inevitable fruit and therefore is really still modernism. It engenders relativism but as a result is self-contradictory since its claim that there are no absolute statements of truth is itself an absolutist statement of the truth.
You can begin to see the problem of trying to push God out of your view.
(Update: modification to the first point.)