2 Augustine replied: The pious Faustus is pained because Christ is cursed by Moses. His love for Christ makes him hate Moses. Before explaining the sacred import and the piety of the words, "Cursed is every one that hangs on a tree," I would ask these pious people why they are angry with Moses, since his curse does not affect their Christ. If Christ hung on the tree, He must have been fastened to it with nails, the marks of which He showed to His doubting disciple after His resurrection.
Accordingly He must have had a vulnerable and mortal body, which the Manichæans deny. Call the wounds and the marks false, and it follows that His hanging on the tree was false. This Christ is not affected by the curse, and there is no occasion for this indignation against the person uttering the curse. If they pretend to be angry with Moses for cursing what they call the false death of Christ, what are we to think of themselves, who do not curse Christ, but, what is much worse, make Him a liar? If it is wrong to curse mortality, it is a much more heinous offense to sully the purity of truth. But let us make these heretical cavils an occasion for explaining this mystery to believers.
Source: Reply to Faustus the Manichaean (New Advent)