Problem: According to this verse, “these are the words which Moses spoke.” However, many biblical critics claim that Deuteronomy was written in the third century b.c., many centuries after Moses’ time.
Solution: There are many arguments that support the claim that Moses wrote the Book of Deuteronomy.
Second, Joshua, Moses’ immediate successor, attributed the Book of Deuteronomy to Moses, exhorting the people of Israel to “observe to do … all the law which Moses … commanded” (Josh. 1:7).
Fifth, our Lord quoted the Book of Deuteronomy (6:13, 16) as the authoritative Word of God when He resisted the devil (Matt. 4:7, 10), and He also directly attributed it to the hand of Moses, saying, “Moses said” (Mark 7:10) or “Moses wrote” (Luke 20:28).
Sixth, the geographical and historical details of the book display a firsthand acquaintance such as Moses would have had.
Seventh, scholarly studies of the form and content of Near Eastern covenants indicate that Deuteronomy is from the period of Moses (see Meredith Kline, Treaty of the Great King, Eerdmans, 1963).
In addition to all of this, the apparent references within the book to a later period are easily explained (see comments on Deut. 2:10–12). Of course, the last chapter of Deuteronomy, being about Moses’ death (chap. 34) was probably written by his successor Joshua, in accordance with the custom of the day.