The epistles of Paul are the roadmap and foundational texts for Christian belief, Christian practice, Christian theology, Christian ethics.Obviously much of Genesis is allegorical. But are the "history" books also supposedly allegorical?
I know you don't like standard Christianity which integrates both the OT and the NT but we are stuck with a God in the NT that is, per every single line of the NT, the same God as the OT.
Pretty much the only importance of the Hebrew Bible in Paul's epistles is as prophecy and reference material.
You are welcome to stress about the Old Testament as much as you want. I'm sure if you read it as literally as a conservative Southern Baptists do, you can pick apart and mock many of the Jewish stories in the OT.
I'm convinced setting up strawmen like that is precisely the agenda atheists have, because 99 percent of the complaints they have about Christianity are about the Old Testament.
As far as my understanding goes, the Old Testament is important for prophecy and background reference.