Herman Bavinck anticipates Lewis in his his section on General Revelation in the Prolegomena to his Reformed Dogmatics:
In the Middle Ages Thomas not only asserted that as rational beings human beings can– without supernatural grace– know natural truths but also testifies that it is impossible for there to be “some knowledge which is totally false without any admixture of some truth” and in this connection appeals to the words of Beda and Augustine: “There is no false doctrine which does not at some time mix some truth with falsehoods.” The Reformed theologians were even better positioned to recognize this by their doctrine of common grace. By it they were protected, on the one hand, from the Pelagian error, which taught the sufficiency of natural theology and linked salvation to the sufficiency of natural theology, but could, on the other hand, recognize all the truth, beauty, and goodness that is present also in the pagan world. Science, art, moral, domestic, and social life, etc., were derived from that common grace and acknowledged and commended with gratitude. As a rule this operation of common grace, though perceived in the life of morality and intellect, society and state, was less frequently recognized in the religions of pagans. In the latter context the Reformed only spoke of natural religion, innate and acquired, but the connection between this natural religion and the [pagan] religions was not developed. The religions were traced to deception or demonic influences. However, an operation of God’s Spirit and of his common grace is discernible not only in science and art, morality and law, but also in the religions. Calvin rightly spoke of a “seed of religion,” a “sense of divinity.” Founders of religion, after all, were not impostors or agents of Satan but men who, being religiously inclined, had to fulfill a mission to their time and people and often exerted a beneficial influence on the life of peoples. The various religions, however mixed with error they may have been, to some extent met people’s religious needs and brought consolation amidst the pain and sorrow of life. What come to us from the pagan world are not just cries of despair but also expressions of confidence, hope, resignation, peace, submission, patience, etc. All the elements and forms that are essential to religion (a concept of God, a sense of guilt, a desire for redemption, sacrifice, priesthood, temple, cult, prayer, etc.) though corrupted, nevertheless do also, occur in pagan religion. Here and there even unconscious predictions and striking expectations of a better and purer religion are voiced. Hence Christianity is not only positioned antithetically towards paganism; it is also paganism’s fulfillment. Christianity is the true religion, therefore also the highest and purest, it is the truth of all religions. What in paganism is the caricature, the living original is here. What is appearance there is essence here. What is sought there can be found here. Christianity is the explanation of “ethnicism.” Christ is the Promised One to Israel and the desire of all the Gentiles. Israel and the church are elect for the benefit of humankind. In Abraham’s seed all the nations of the earth will be blessed.
~Reformed Dogmatics Vol.1, 319-320