Natural Theology is not the claim that all the truths of Christianity can be proved via human reasoning, without the aid of divinely inspired scriptures. Rather, Natural Theology, properly understood, does not venture to say anything about that which can be known only through divine revelation, such as, that Jesus was born of a virgin, that Jesus is God, that God is Triune, etc. Having made these distinctions, we are now in position to ask if Natural Theology, understood as that which can be known about God via rational human observations of our Universe (including ourselves), is a necessary part of protestant orthodoxy.

NATURAL THEOLOGY AND PROTESTANT ORTHODOXY” BY DAVID HAINES IN GOD OF OUR FATHERS: CLASSICAL THEISM FOR THE CONTEMPORARY CHURCH, ED. BRAD LITTLE JOHN, 59.