Having written about the Reformed orthodox endorsement of metaphysics (though not a simply agreed upon endorsement, it must be said; there was debate about the role and limits of philosophy in theology among the Reformed), it is also important, in order to fill out the historical picture a bit further, to note a common line of argument among the Reformed orthodox regarding the source and limits of natural theology.
While on the one hand, many Reformed were concerned to go beyond the reduction of metaphysics by such groups as the rationalist Socinians, they were on the other hand concerned also to limit what they regarded as an excess of metaphysics by many Roman Catholic groups. The result of this excess, they argued, was that principles of metaphysics came to be considered as principles of theology, and reason was promoted to the role of a judge of the faith.