The issue of the historicity of Adam is not only the inerrancy of the
Scripture or a particular theory of salvation, but rather the UNITY OF
GOD'S REVELATION in Nature or in Scripture. I have explained this in some
details in my paper on Progressive Creationism (JASA, Vol. 39, 3.87, p.
9-19) and will just make a few comments here:
(1) The denial of a unique human couple who sinned and were banished from
God'd blessing and to recognize the existential nature of evil and the
need for redemption is to subscribe to a DUALISTIC approach which
compartmentalize reality in a long run: the spiritual realm and the physical
realm become independent of each other.
(2) The major weakness of this approach is the inconsistency of allowing
God to act on a personal level through existential encounter while
denying God's action in history throough creation. The religious truth,
as revealed by a personal encounter with the incarnate Word through whom
all of the Scripture should be interpreted, seems to be divorced from the
historical truth of the Bible. The lack of interaction between the
religious truth as expressed in mythical language and the historical
truth as expressed in scientific language seems to imply that reality is
comprised of several levels of truth that are independent of each other.
(3) The bodily resurrection is a major demonstration of how religious
truth is dependent of the historical truth. (I Cor. 15: 17-19)
(4) A major theological conference held at Trinity Evangelical Seminary
in 1989 where over 600 leading evangelical theologian of N. America
gathered has produced a theological treatise (Evangelical Affirmations,
ed. Ken Kantzer and Carl Henry, 1990, Zondervan) in which the historical
Adam and a historical Fall is affirmed as essential to the evangelical
faith.