According to Moshe's speech in Parshat Va'etchanan, the primary significance of Ma'amad Har Sinai is God's direct revelation to Israel. However, the description of Ma'amad Har Sinai in Sefer Shemot focuses on Israel's belief in Moshe as a true prophet. By closely examining the two instances of revelation, one can see that the purpose of the speech in Devarim was to establish the faith for all generations even when individuals and the community as a whole do not experience a revelation as had occurred during the exodus from Egypt or at Mount Sinai. From here it follows that faith in the book of Devarim rests on the foundations of prophecy, memory, and story, and not on unmediated experience.

Courtesy of the Virtual Beit Midrash, Yeshivat Har Etzion