There is no such thing as a talking snake, therefore why should I believe that Adam was real either?
Consider also that Jesus, the second and last man, or last Adam (1 Cor. 15:45, 47), treated Adam and Eve as historical beings. Jesus refers to Genesis 1-2 in Matthew 19:4-6 saying:
He answered, "Have you not read that he who created them from the beginning made them male and female, and said, 'Therefore a man shall leave his father and his mother and hold fast to his wife, and the two shall become one flesh'? So they are no longer two but one flesh. What therefore God has joined together, let not man separate."
Genesis 3:15 speaks of Christ himself (eg. Isa. 53:10; Gal. 4:4-5) – and he is real! And the in-the-garden Adam is in the lineage of Jesus Christ given in Luke (Luke 3:38), therefore without this first in-the-garden Adam, there wouldn't have been the second Adam, Jesus Christ. Did Jesus exist? Of course he did (1 Cor. 15:5-8). The apostle Paul viewed this in-the-garden Adam as a historical person and used him to set up a comparison with Christ (Rom. 5:12-19). If the first Adam is fictional and not a real human being, then there couldn't be a genuine comparison, because Jesus had to be a genuine human being in order to atone for the sins of his people.
The first Adam and the second and last man Adam are very, very real. Don't let a talking snake mislead you.
Dr. Joseph R. Nally, Jr., D.D., M.Div. is the Theological Editor at Third Millennium Ministries (Thirdmill).