To whom were the writings from Genesis 12 through Paul's epistles directed?
Everything from Genesis 12 up until Paul's epistles was directed primarily, if not exclusively, to the Jew, especially while he was under the law. Paul was later commissioned at Damascus to go far hence to the Gentiles, and by revelation received truths not found elsewhere in Scripture.
Les explains that everything from Genesis 12 up until Paul's epistles was directed primarily, if not exclusively, to the Jew, especially as he was under the law. But Paul was commissioned right away at his conversion at Damascus, when God told Ananias He would send this man far hence to the Gentiles. God then took Paul out in the desert and gave him revelations that Paul later refers to in Galatians chapter 1, making known by revelation things that would come from his pen and are not found anywhere else in the Bible. Les also notes that Paul says all Scripture is inspired of God, all of it from cover to cover, and profitable for everyone, so Paul never lifts himself up as the only one to heed. Yet Paul brings out many doctrines not found elsewhere, so it behooves us to spend the best part of our time in Paul's epistles and funnel back and forth throughout all the rest of the Scriptures.