I strongly believe that JPII’s comments represent his opinion about the advisability of using capital punishment in current social conditions. If it is opinion then it is not doctrine and Catholics may disagree with it (a point Cardinal Ratzinger made).
Because (if) it is opinion it should not be treated as doctrine; we should accept it for what it is and recognize that, as doctrine, it would repudiate all that the Church had taught about capital punishment for pretty much her entire history. Second, yes, I believe that he was mistaken in his opinion. The Church has always based her position on the need for capital punishment on Genesis 9:6, which explains that the penalty for murder is death *because *man is made in the image of God. This explains why, even as support for the death penalty was generally diminishing, it was strongest within Christian enclaves. We have reversed the meaning of that passage from “we must execute the guilty because the life he took was sacred” to “we may not execute the guilty because his life is sacred”.
*If the Pope were to deny that the death penalty could be an exercise of retributive justice, he would be overthrowing the tradition of two millennia of Catholic thought, denying the teaching of several previous popes, and contradicting the teaching of Scripture (notably in Genesis 9:5-6 and Romans 13:1-4). * (Cardinal Dulles, 2002)
The death penalty is not intrinsically evil. Both Scripture and long Christian tradition acknowledge the legitimacy of capital punishment under certain circumstances. The Church cannot repudiate that without repudiating her own identity. (Archbishop Chaput, 2005)
*Their [the pope and bishops] * prudential judgment, while it is to be respected, is not a matter of binding Catholic doctrine. To differ from such a judgment, therefore, is not to dissent from Church teaching. (Dulles, 2001)
Ender