Oworm - good points all.
I think, however, that there are a few points that bear examination.
If Adam is not literal, did Paul lie? No. A few points:
1. I'm quite prepared to accept that Paul considered Adam to be literal. He would have had no real reason to suppose otherwise. Consequently he is not lying but saying what he believes to be true
2. The question we must ask is - 'does Paul's theology here collapse if Adam is not literal?' It is my contention that it does not.
It seems to me that the thrust of Paul's argument is that we are all the people of the same God, indeed His offspring. I'm far from convinced that the literality of Adam is essential here; it certainly illustrates the point, but so does common ancestry, as it happens. One of evolution's contributions to humanity (contra Morris, Hovind et al.) is the recognition that we are one race, the human race, of a common origin. Paul, in his context, talks about us as "sons of Adam". We in a scientific context might demonstrate it differently, but the point is the same.
Moving on to Romans, Paul is explaining the work of Christ by comparing Christ as a type with Adam as a type. The literal existence of the type is neither here nor there; it is a matter of historical record that Christ was literally real; equally I would contest it is a matter of historical record that Adam was not. No matter; Paul uses the OT story to explain how the work of Christ can be effective for all people. Seeing Adam as a type - indeed, the nearest Adam comes to literality is when I look in a mirror - solves a theological problem, which is the injustice of God condemning me for what an ancestor did. No, He condemns me because of what I do. In this way, I am Adam. I sin, and my sin affects other people, causing both suffering and further sin.
This is how I see it - suppose I launch a physical assault on someone. The consequences are:
(1) immediate suffering of another person
(2) that person being likely tempted into sinning against me by launching an attack in retaliation.
(3) breaking of relationship - must have been bad anyway, but now it's worse.
It goes further - because of the widespread sinfulness of human institutions, I can hardly buy clothing or coffee without participating in the sinful actions of the corporations that control markets in these items. I am forced into the web of sin.
It is methinks in this way that the sin of one causes condemnation for another - we are a race of Adams. screwing each other up.
This is the mercy of God - just as our sin screws up other people, Jesus' work redeems other people. It's only a tiny part of a model of atonement, but it is the one Paul's referring to here. Not only a technical change in status in God's Bad Books, but also there is the intention that with the Holy Spirit living in us bringing in the Kingdom of God in our actions, we can lessen the "web of sin" I describe above, and be less contributors to it through refraining from sinful actions that damage others.
Whew - what a sermon!
If Paul was wrong about the historicity of Adam I don't think it means our Bibles are valueless except for as far as they burn; the theological message (which I have expounded above) is untouched. Really, Paul's being wrong about this point is of no more import than the writer of Joshua thinking that the sun went round the earth.
