In target shooting there are two kinds of score, one that refers to proximity to a target and one that refers to proximity to other shots. Scoring well by virtue of consistency is called good grouping. If all my shots are close together, but far from the bull’s eye, I am said to have scored well in regards to grouping and poorly in regards to proximity to the target.
To construct a doctrine of God without reference to the Bible may obtain good grouping, but will be nowhere near the bull’s eye. This, it seems to me, is rather like natural theology. If you set your sights according to your own mind, human, autonomous reason, that’s how you will aim. Natural theology does not take into account our faulty sights, naturally pointing away from God.
In order to shoot straight we need our sights adjusted. This is what the Bible calls new birth. And to be born again it is necessary to hear the gospel proclaimed. The Bible, as we read it, live by it and love it, adjusts our sights; it gives us the knowledge of God. In other words, we need the Bible in order to be born again and then we need it to be conditioned to know God better over time. We need the very thing we are denied with natural theology to do proper theology, to shoot straight.