Scripture does not directly answer this question, but a few things can be inferred and a few possibilities deduced. First, it is clear that unlike the census of Moses Num. 1:2), this did not come at the command of God. 2 Sam. 24: 1 records, “the anger of the LORD was kindled against Israel, and he moved David against them” (NKJV). This must be harmonized with 1 Chron. 21:1 which says “Satan stood up against Israel, and moved David to number Israel.” How can both statements be correct? 2 Sam 24:1 must be understood in terms of what God allowed Satan to do, not direct action on the part of God. This may be compared with Job 2:3. After Satan is allowed to bring trial upon Job, God says to Satan, “he holds fast to his integrity, although you incited Me against him, to destroy him without cause.” The same word is used in 2 Sam. 24:1 (“moved”) and Job 2:3 (“incited”). Although one concerns God and David, and the other Satan and God, it is interesting because of what is demonstrated in God’s own words. Satan “incited” God “to destroy” Job, but God did not act directly—He allowed Satan to act and God speaks of this allowance as His own action. In the same way, God allowed Satan to act to “move” David, but 2 Sam. 24:1 speaks of God’s allowance as God’s action. If this is the only factor we see that David did not act by the command of God, but acted presumptuously to take this action.
A second possibility concerns David’s motive. The text doesn’t really identify David’s motive. There may be some inference, however, that this was for military or political reasons. Why would this be an offense to God? A principle that runs throughout God’s covenant with Israel concerns the issue of numbers as it reflects trust in God. In Deut. 7:7 God declared, “The LORD did not set His love on you nor choose you because you were more in number than any other people, for you were the least of all peoples.” When God sent Gideon to lead the Israelites, He declares, “The people who are with you are too many for Me to give the Midianites into their hands, lest Israel claim glory for itself against Me, saying, ‘My own hand has saved me’” (Judges 7:2). David, as a young man, understood this. He told Goliath, “the LORD does not save with sword and spear; for the battle is the LORD's, and He will give you into our hands” (1 Sam. 17:4). It may be that David, in his old age has either forgotten this or lost the same faith in God he had as a young man. Joab’s concern was about numbers. He hoped that the people would be multiplied “a hundred times more than they are” (2 Sam. 24:3; 1 Chron. 21:3) but feared David’s action would bring guilt. God’s punishments He offers all concerned a reduction in numbers (1 Chron. 21:11-14). God essentially forces on David a reduction of numbers comparable to the voluntary reduction asked under Gideon. This may indicate to us that at least part of the sin concerned misguided confidence. Hezekiah is the antithesis of this. When he learned of the threat of Assyria he looked to God and the “Angel of the Lord” killed Assyrians, not Israelites (2 Kings 19). David was not personally punished. He, along with the nation as whole was forced to remember that their strength rested in God, not in their own numbers. It is interesting that in the next generation (in spite of this reduction due to the plague), Israel grew to its largest extent in its history (cf. 1 Kings 4:21-24). Israel’s defensive strength always rested in God.
Kyle Pope, March 2011