Along with Karl Barth, Emil Brunner may be identified as an important representative figure of what Unificationism calls the "third reformation"—the third stage of the "Abel-type view of life" during the 400-year "Period of Preparation for the Second Advent of the Messiah." He effectively criticized the nineteenth century liberal theological view that Jesus was simply an ideal man and emphasized the need for repentance and faith in Christ as the living Messiah and incarnation of God. From the standpoint of the Divine Principle, Brunner was also correct to disagree with Barth about the question of the effects of original sin, affirming that humans retain a "point of contact" with God even after the Human Fall, similar to the DP idea of the "original mind."
At the same time, while Brunner's faith-affirming view has much to commend it, we also need to be cognizant of the fact that liberal theology, too, has much in common with the Divine Principle. It emphasized that Jesus was a man like us, rather than God Himself, demonstrated that the Bible is not the Truth itself but (in DP's words) a textbook teaching the truth, and affirmed the crucial importance of human effort in realizing God's kingdom.
In the final analysis, the highest stage of "Cain-type" and "Abel-type" Christian theologies did not boil down to a question of either/or, but of both/and. As Reverend Sun Myung Moon has often reminded his followers, both Cain and Abel have something important to offer.