Natural theology is discursive and progressive being a human discourse about God apart from Scripture. How then can we philosophically understand God unless guided by special revelation? It is even special revelation that explains that God’s attributes are understood from what is created (ROMANS 1 ETC).
I think some people confuse Natural philosophy with General Revelation, which is immediate, perspicuous, non-propositional knowledge of God which is suppressed by sinners everywhere to their own judgment. Unless we base our philosophical thinking upon our biblically derived theology, we are deluding ourselves that we have the same God. The apostle Paul pointed to the biblical God of nature and providence when he dialogued with the philosophers and led them to hear of Jesus and the resurrection.
Smithy, it seems you have left out an important part in your description/definition of natural theology: “Natural theology is discursive and progressive, being a human discourse about God apart from Scripture based upon God’s general revelation of Himself.”
Scripture is part of God’s specific revelation, but God reveals Himself in a general way in nature. And yes, natural theology is a human and fallible activity (as any attempt at theology is), but it is a reflection on what God reveals about Himself in nature.
It would also be correct to say that belief in God is properly basic (a belief that is “immediate and perspicuous”, as you say, and not dependent on argument and evidence) based upon the inner witness of the Holy Spirit (of whom knowledge can be, and often are, suppressed). But why would this be in opposition to reflecting philosophically upon God’s general revelation of Himself in nature and thus inferring true beliefs about God?
So, if the results of natural theology based upon general revelation reveal attributes of God that are the same as the attributes discovered theologically based upon studying specific revelation (i.e., God’s Word), then how are we NOT talking about the same God with respect to those attributes? Of course, we don’t get the same comprehensive picture of who God is through natural theology as through Biblical theology, but surely that speaks to the limits of natural theology, not its falsity or delusionary properties.