When you support the death penalty, you commit yourself to the proposition that you support the cold-blooded murder of innocent people, since the Innocence Project has show that about 4% of the people we kill were wrongly convicted.
On the other hand, if you just listen to the Church’s guidance and agree that the death penalty should be abolished, you need never have another person’s death on your conscience again. Plus, abandoning support for the unnecessary slaughter of human beings not only makes you more credible when you claim to be prolife, it frees up your time from fighting the Church on behalf of right wing culture war demagogues so that you can devote your time to fighting abortion. Win win!