Christianity has no monopoly on circular reasoning. Ask any Jew about the notion that we are the Chosen People. How do we know God chose us? It is written in the Torah. Who wrote the Torah? We did. Duh. Even if your answer to the second question is "God wrote the Torah" the follow up question, "Who says God wrote the Torah?" ends up in the same place. Jews say God wrote the Torah. Even Christians and Muslims who also claim the Torah is divine revelation base their claims on the Jews.
One cannot escape the fact that in the end it is the individual who decides what is true or false for her or himself. Given the fact that we have no objective way of determining this, our conclusions should be drenched with humility.
Anyway, back to our text?