First let me say I have not in favor of capital punishment, not on moral grounds, but because we don’t do it consistently and fairly and I doubt we will ever be able to, so we shouldn’t do it at all. Also, I don’t think it works to deter crime, give closure to victims or even to punish. To my mind, life in a maximum security prison would be worse. But I think this new stance of the church is hypocritical.
We believe that Our Church is Apostolic. That means we are taking credit for an unbroken line of Popes’ succession from Jesus on Earth. It follows then, we also have to take the responsibility for what that unbroken succession has done. It is not enough to apologize for it, we have to own it, or it’s hollow.
Sadly, Our Church has been responsible for an extraordinary amount of capital punishment over its two millennia, many times for lesser crimes than capital punishment is used for now. The Church has caused people to be put to death for heresy, witchcraft, etc. And The Church has caused people to be put to death in more horrible ways: Burning, torture. etc. If we distance ourselves from that past, we also distance ourselves from the claim of Apostolic succession. If bishops who supported the Crusades and the Inquisition elected Popes, which they did, how can those Popes be the successors of Christ? If they are not, there goes Apostolic Succession. If they are, then this Pope is being duplicitous.
Also, I think this new direction of The Church is a step over the line of separation of church and state. Capital punishment, unlike abortion and euthanasia, is a political thing because governments do it, not individuals. So while the Pope may have a strong opinion about it, he has no power over it. Governments don’t go to Confession.