Parshat ואתחנן is full of numerous laws mixed with a little bit of philosophy. In essence, Moshe Rabbeinu is showing the truth of Judaism as compared to other religions. He reminds the people all of the outstanding miracles they witnessed in Egypt with the ten plagues, splitting of the Red Sea, and the revelation at Sinai. Moshe says flat out that no nation or religion can make the claim of the truth of their religion as Judaism can. Can any nation claim that their G-d took one nation from the midst of another with signs and wonders as He did for עם ישראל. Can any nation claim that every single member actually heard Hashem speak, as you saw and heard. The Kuzari uses this line of reasoning as evidentiary proof of the truth of Judaism as well. He adds that the Christians and Muslims both acknowledge that the events in the Torah are true. We only need to study Torah in order to reinforce our convictions and beliefs.