Genesis in history

I am in a Hebrew exegesis class on Genesis 12-36. The class centers around the life of Abraham and deals with issues of faith and culture in the pre-Israelite land of Canaan. I will write a post perhaps on the faith of Abraham at another point, this rant will deal mainly with issues of scholarship on the book of Genesis and the life of Abraham.

For my faith in Christ to be valid, two conditions (involving Abraham) have to be met.

1. He has to have been a historical person. If Abraham was merely a composite figure*1 (like most German Old Testament scholars believe), or a theological character*2, then nothing Jesus Christ offers me can be true. 1*A composite figure is a character in a story that is made up of pieces of real historical figures. For example, in the sitcom Seinfeld, George Kastanza is a composite character involving real pieces of the writer for the series. 2*A theological character is kind of like an allegorical picture of the theological points a society most values. For example, many German liberal scholars believe the Hebrews prized faith in God's promises even in adverse circumstances, so they invented or embellished a character who was faithful to God's promise even when childless and in old age. The events weren't "real", but they were portrayed to teach virtue, not history.
If Abraham is not a historical person, then there is a problem for the idea of redemption. Abraham enters the story of Genesis at humanity's bleakest point. The flood has killed off almost the entire population, and now the remaining humans detest God's plan for them to be fruitful and fill the earth. They set up an alternative society at Babel in order to rebel against God, and he confuses their languages and sends them scattered. In the midst of the "barrenness" of humanity, a barren couple (Abram and Sarai) are chosen by God to leave their own society. When Genesis 12:1 starts, it is the changing of Genesis from God's scattering of an alienated humanity to his gathering of a redeemed humanity. Abram is the fount of redemption in a historical sense. With him starts the election of a seed that will bless all the nations. Now in Romans, Paul talks about this seed and the promise. God's promise to Abram was not based on keeping a law (that came afterwards), but was based on faith. Therefore, all who believe God relate to his promise the same way Abram did.
If Abram did not exist historically, neither did elective redemption, or God's promise to bless all nations through him. If that promise did not exist, the blessing does not exist, and all nations are still scattered from God.
2. He has to have been truly justified by faith. If he was not historical, or indeed justified by faith (see Genesis 15:6), then my faith in Christ is not valid. If there is no historical precedent for justification by faith apart from works of the law, then there is no validity for present justification by faith apart from works of the law. If Paul's example in Abraham is not historical, then our faith is floating in a sea of subjectivity. Subjective faiths are just wishful thinking. I can believe the pink elephants will bring me eternal happiness, and it will help me feel better if I'm drunk and hallucinating; but let my liver digest the intoxicants and I'm back in a reality that is not benefited by pink elephants. Faith in an ahistorical redemption is just like faith in pink elephants.
Historicity seems to be the most embarrasing aspect of Christianity to most scholars today, yet they don't realize (or either they don't care) that it is essential to its value. An ahistorical Christianity is perhaps the biggest waste of time imaginable. I would not waste one second on a religion that says "lose your life to find it" if in fact there was no true life in the waiting for me once I lost it. If that was the case, we are pitiful among all people (see 1 Cor 15, Paul makes the same point about the resurrection). Abraham is one of the fulcrum points in the Bible in which historicity is non-negotiable.

"so that in Christ Jesus the blessing of Abraham might come to the Gentiles, so that we might receive the promised Spirit through faith. " Gal 3:14