There are a couple possible reasons to explain why God ordered a census of the people of Israel in the book of Numbers. God could have commanded the census to reveal His power in redeeming such a large number of people or to list those who were able to serve in war (Numbers 1:3).
The stated purpose of the Israeli census, according to Numbers 1:3, concerned war preparations. This would explain why women were not included in the census and males under twenty were not counted. The census did not leave out women and young people due to anything related to their social status but rather due to their military ineligibility.
Numbers 1:45–46 provides a summary of the census: “All the Israelites twenty years old or more who were able to serve in Israel’s army were counted according to their families. The total number was 603,550.” This count included men from every tribe except that of Levi (verse 47). Interestingly, the tribe of Judah ranked as the largest tribe with 74,600 men (verse 27), noting its importance in the early history of Israel. Judah would be the tribe that remained faithful longer than the rest of Israel and the tribe from which Jesus would arise.
The Levites, who were not counted in the census, were chosen as the priestly tribe. They bore the responsibility for the things of God’s tabernacle and the offerings. Numbers 1:49–50 notes, “You must not count the tribe of Levi or include them in the census of the other Israelites. Instead, appoint the Levites to be in charge of the tabernacle of the covenant law—over all its furnishings and everything belonging to it. They are to carry the tabernacle and all its furnishings; they are to take care of it and encamp around it.”
Finally, a word about the other suggested reason for this census can be helpful. The view that the census was intended to emphasize the power of God in rescuing such a large number of people from Egypt is also valid. God led an entire nation of people through the wilderness, keeping His covenant with Abraham. However, the clearly stated purpose of the census in Numbers 1 was related to military eligibility, an issue that the books of Numbers and Deuteronomy would later emphasize.