To what end did Anselm write his Cur Deus Homo, and what convictions are presupposed in its ideal reader? The answers to these questions are intertwined. Cur Deus Homo is aimed at assuring Christian believers of the reasonableness of their faith, but the believers it addresses have clearly been touched by the doubts of “unbelievers,” who repeatedly voice their objections through the dutiful Boso (e.g., 1.1, 265). What do these “unbelievers” believe? Well, they’re monotheists, to start, who accept “that the rational creation was created righteous, and was so created for the purpose of being happy in the fact of God’s delighted approval?” (1.9, p. 277) They also seem clearly to accept the view that humanity has sinned against God (1.10, 282). However, they maintain, against the church, that God could have saved humanity “through the agency of some other person, angelic or human, or simply by willing it” (1.1, p. 265). They also “object that we are inflicting injury and insult on God when we assert that he descended into a woman’s womb” (1.3, 268).
It should be obvious enough that these unbelievers described here at neither atheists (who of course were rather hard to turn up in this period), nor Christian heretics, nor even the stray Lithuanian animist, but rather Jews and Muslims. The latter group especially would’ve been apt to be on Anselm’s mind as he wrote Cur Deus Homo, which he completed in 1098, two years into the first Crusade. (It’s all the more telling that Anselm dedicated this work to Pope Urban II, of Dieu le veut fame.) This only become fully clear at the work’s end, when Boso comments, “You prove that it is a matter of necessity for God to become man, and you do so in such a way that…you [provide] something which would satisfy not only Jews, but even pagans” (2.22, p. 355).) Applied to contemporaries, of course “pagani” or “paynim” is simply the medieval Christian’s most ordinary way of referring to Muslims. And interestingly, Anselm’s biographer Eadmer reports that Anselm got to know some Muslim mercenaries of the Duke of Sicily who were besieging nearby Capua in 1098, as he was finishing Cur Deus Homo (cf. Vita Anselmi 111-12, apud Asiedu, “Anselm and the Unbelievers,” p. 547).
The point of the work, on this reading, is to equip Christians to understand how the theological commitments they share with Muslims and Jews require the Incarnation. After they’ve elaborated the plight of sinful humanity, Boso wonders, “How then will man be saved, if he does not himself pay what he owes, and is bound not to be saved if he does not pay?” (1.25, 313). And to this, Anselm responds, “You ought to demand an answer now from those people, on whose behalf you are speaking, who do not believe that Christ is necessary for the salvation of mankind” (1.25, 313). The punchline of the first part of the Cur Deus Homo is that you can’t accept the createdness and sinfulness of humanity and not also accept that there is a Jesus-shaped hole in the biblical story.