A recent banner outside a Congregational Church in my hometown:
"Our faith is two thousand years old. Our thinking is not."
The total divorce of faith from reason--and the resulting divorce of Christian from Christian--is nowhere more evident. I will have to extrapolate, of course, and guess that what the banner means is this: "We accept everyone regardless of race, creed, lifestyle, sexual orientation, etc., etc. Other Christians (whose thinking is still two thousand years old) do not. Our common faith in Jesus has no bearing on how we think about human behavior."
If what we believe (our faith) is so far removed from what or how we think, then we are truly fragmented creatures. Faith is simply a gift of God--"having the mind of Christ." It is a point from which we encounter and think about the world, ourselves, and our Creator. If faith does not inform our thinking, it is as dead as St. James's "faith without works." It's just a pacifier that makes us feel happy on Sundays.
Reason informed by faith, however, receives the gift of a new viewpoint: the world is finite, the Creator infinite; man is created, fallen, and redeemed; the virtues have meaning beyond "manners." All sorts of new possibilities open up to the human mind, including, I might add, modern science.
But if you refuse to let a two thousand year old faith inform your thought--fearing it might be "backwards"--you have also failed to truly believe that faith in the first place. The Christian faith came to the world two thousand years ago. Its truths, however, are yesterday, today, and forever.