mark kennedy said:
It's hardly irrelevant if Noah and his family like Adam and Eve are literal historical figures. I am looking for Biblical and theological reasons for the historicity of Adam but Noah is important as well.
The most common theological reason I know of for believing that Adam and Eve were literal historical figures (and thus Noah as well) is that if they were not "literal historical" people, then the doctrine of salvation through Christ is false and/or meaningless.
The thought runs more or less like this. Jesus represents a "second Adam" - what that means isn't really clear, but as Adam literally is "man" then it means that Jesus is the "second man", as opposed to the "first man." The first man was tainted by sin, and by extension all humans are tainted by sin. The "second man" is then separate, and not tainted by this sin. This second Adam is seen as the necessary sacrifice to overcome and defeat sin, and thus by extension, the wages of sin - death. It is implicit in Genesis 3 that part of God's curse on Adam and his descendants is that they will not enjoy eternal life, but will instead die, as a consequence of sin.
Now, if Adam is NOT a historical figure, say proponents of this idea, then Jesus's sacrifice was in vain, because sin and death did not enter via Adam. This would mean, then, that there was never a state of perfection in the "first man" and thus, there is no perfect state we can be restored to. That, after all, is a common concept of what salvation is - restoration to that perfect state. If there was never such a perfect state, how can we be restored to it?
Of course, there is the alternative idea that yes, indeed, humans never started in a perfect state at any time in history, but we can strive to be elevated or elevate ourselves into that perfect state, or close to it. This is somewhat akin to Buddhist and Hindu belief. In fact, it is interesting to note, Buddhists and Hindus do not ignore Jesus, but in fact frequently view Jesus as having been such a person - one who learned the path toward elevation to perfection, and the story of his ministry of love and repentance, of selfless sacrifice, is Jesus's way of pointing the rest of us toward this perfect state. (You can find Buddhists who do think of Jesus as having been close to a perfect Buddha, or possibly even WAS a Buddha.)
To some degree, this also reflects Methodist belief. Wesley did not believe in the idea that humans inherit sin from Adam - for him, the doctrine of Original Sin made no sense. Wesley held that we are born sinless and are essentially blank slates... but we have the capacity for sin, and inevitably we all do fall prey to this capability. Thus, following Christ is the path to overcoming this capacity and tendency toward sin. In essence, it is progressing beyond our baser nature and striving toward the perfection exemplified by Christ.
Actually, the concept of humans having started as "perfect" but eventually descended into a fallen state (whether suddenly or gradually) is pervasive in many Western philosophies and religions. The ancient Greeks, for example, believed that human history proceeded through several ages, starting with a Golden Age (perfection), a Silver age, then a Bronze age, and so on, down to their "modern times" in which humans lived very short lives, had lost much of the miraculous technology of previous ages, and so on. This belief has even made its way into some Christian views today - you can find people who believe that Adam and Eve weren't even the original "humans" but were the final creation of humans, and that Genesis 1 indicates an earlier creation (and that even Job represents an earlier age, because in Job you have Satan residing in Heaven - which could not have been true according to the Genesis 2 story if the serpent = Satan).
