In his commentary on 2 Samuel (part of the excellent Anchor Bible series), P. Kyle McCarter, Jr., offered the following reasoning behind why the taking of a census would result in God inflicting divine judgement and wrath upon the people in 2 Sam 24:
Census and Plague
Why should the taking of a census produce a plague? The present account in the form we have it indicates that the census was a sin of the king (v. 10) and the plague, therefore, was a punishment for sin (v. 13). This was certainly the view of the prophetic circles in which the final form of the account derives (see below). The census was a sin (perhaps) because of the administrative innovations it implied, viz. fiscal reorganization and military conscription 9c. Bright 1972:201, 246; Cross 1973:227, 240). Such observations, however, beg the larger question of the relationship between census and plague, because prophetic theology side, there was an “ancient taboo of counting heads” (Sanders 1962). Independently of the present passage, for example, Exod 30:11-16 provides for a “life’s ransom” (kōper napšô, v. 12) for every Israelite counted, “so that there will not be a scourge (negep) among them when you count them.” Thus we must first see an explanation of the old religious belief in the connection between census and plague.
Speiser (1958) has attempted to provide such an explanation by drawing on information about the census from the Bible and from the archives of the Middle Bronze Age city of Mari, in northwestern Mesopotamia (cf. Kupper 1950; 1957:23-29). Noting that census taking involved ritual purification in both Mari and Israel, Speiser asks what the cultic element in the census might be. He finds the answer in the practice of taking names and keeping written records, concluding (1958:24):
There must have been a time when the Near Easterner shrank from the thought of having his name recorded in lists that might be put to unpredictable uses. Military conscription was an ominous process because it might place the life of the enrolled in jeopardy. The connection with the cosmic “books” of life and death must have been much too close for one’s peace of mind. It would be natural in these circumstances to propitiate unknown powers, or seek expiation as a general precaution.
Useful as Speiser’s study is, his conclusion I not entirely convincing. It is not clear that name taking was a part of the Israelite census: In Num 4:32, which Speiser cites (p. 23) běšēmôt, “by names,” seems to be added precisely because the case is exceptional. Moreover, Speiser does not give attention to the rules of purification regarding military service, conscription for which was, as he notes, the primary purpose of the census. By retracing some of the ground charted out by Speiser, we shall arrive at a somewhat different destination.
At Mari the noun tēbibtum and related terms, which ordinarily refer to cultic purification, were used to refer to the census (Kupper 1950; Speiser 1958; cf. Kupper 1957:23-29). In Israel, as we have been, anyone enrolled in the census was required to pay a “ransom,” kōper, a term elsewhere referring to ritual purification from the unavoidable or excusable contamination with guilt of a person in a situation requiring purity (Lev 17:11; Num 8:19; 18:22-23; etc.; cf. Milgrom 1976a:80). To be enrolled in a census, therefore, one had to be ritually purified. In the absence of such a purification, a plague could result, exactly as in Num 8:19, where the Levites who attend the sanctuary are described as “making random for” (lěkappēr ‘al; cf. Exod 30:15) the Israelites, so that a plague (negep) will not break out if they encroach on the sanctuary, another violation of rules of purity. Plague, in other words, could result if purity regulations were not carefully followed. The half-shekel kōper of Exod 30:12, then, was a precaution against a breach of purity laws. But what were the purity laws to which an Israelite enrolled in the census was subject?
It is widely acknowledged that “the major purpose of the census in the ancient world was always to lay the basis for levying taxes and registering men for military service” (Bright 1976:198; c. Mendenhall 1958:53-54). The biblical materials show clearly that the census was expected to provide an estimation of available military manpower. According to Num 1:2-3 (cf. Exod 30:14) the Israelites to be enrolled in the census were males twenty years old or older, “everyone able to march with the army (kol-yōṣē’ ṣābā’).” In David’s census, too, it was “men who drew the sword” who were counted (v. 9). Now military duty was a sanctified occupation involving a complex set of laws of purity: A soldier was consecrated before battle (Josh 3:5), the battle camp was kept ritually clean (Deut 23:10-15 [23:9-14]), etc. Once enrolled in a census, therefore, an Israelite was subject to military rules of purity. Any infraction could lead to disastrous results. This is the reason that David’s census order put Israel in jeopardy. The onset of the plague suggests that taboos were violated, as would be almost inevitable in a general enrolment. Was the precautionary half-shekel kōper paid? If such a provision was in effect in the time of David, it must have been neglected, as Speiser supposes (1958:22). (P. Kyle McCarter, Jr., II Samuel: A New Translation with Introduction and Commentary [AB 9; New York: Doubleday, 1984], 512-14)
