It is not a Christian position to believe that Adam was a mythical figure.  Denying the historicity of Adam and Eve opens the door to many theological problems.  Francis Schaeffer expanded on this and said denying Genesis 1-3 also leads to moral problems.

If a person denies the factual historicity of Genesis 1-3 that person has cut himself or herself off from some of the major truths of biblical Christianity.  Others have explained this well: if you deny the fact that Adam was a historical human being, you are far out of step with Jesus’ teaching (Mt. 19:5) and the apostle Paul’s (Rom. 5:14; 1 Cor. 15:22).  It is not a Christian position to believe that Adam was a mythical figure.  Denying the historicity of Adam and Eve opens the door to many theological problems.  Francis Schaeffer expanded on this and said denying Genesis 1-3 also leads to moral problems:

There was a time before the fall, and then man turned from his proper integration point by choice, and in so doing, there was a moral discontinuity; man became abnormal.  Remove that and the Christian answer in the area of morals is gone.  Often I find evangelicals playing games with the first half of Genesis.  But if you remove a true, historic, space-time fall, the answers are finished.  It is not only that historic, biblical Christianity as it stands in the stream of history is gone, but every answer we possess in the area of morals in the area of man and his dilemma, is gone.

Francis Schaeffer, He Is There and He Is Not Silent, p. 35

Rev. Shane Lems is a minister in the Orthodox Presbyterian Church and serves as pastor of Covenant Presbyterian Church in Hammond, Wis. This article appeared on his blog and is used with permission.