Ok, we started out with the Commandment “Thou shall not kill” and the other 9 with Moses on Mt. Sinai. Absolutely a Dogmatic teaching; it cannot change and has not changed. Moreover, a core belief or teaching that belongs to the corpus of Faith and Morals is infallible and cannot be dissented from without sin. Without believing that – which you already said you do not and that you do not care – it will be difficult for you to understand. But if you’d like to try, I will attempt an explanation.
Core beliefs and dogmatic teachings do not change; our human understanding can change. While we cannot ever know everything about God, we can come to understand a bit more than we did as children. The Dogma is not a moving target – but we have the capacity to mature in our spirituality. We can change.
The Church has always recognized the tension between the death penalty and the 5th Commandment. However, the Church has to honor not just the 5th commandment, but also the 8th too.
Look at this statement from the Catechism of the Council of Trent:
“The power of life and death is permitted to certain civil magistrates because theirs is the responsibility under law to punish the guilty and protect the innocent. Far from being guilty of breaking this commandment [Thy shall not kill], such an execution of justice is precisely an act of obedience to it.
For the purpose of the law is to protect and foster human life. This purpose is fulfilled when the legitimate authority of the State is exercised by taking the guilty lives of those who have taken innocent lives.” - Part III, 5, #4, emphasis added
The moral principle that applies here is life. (Interestingly, it’s also the same moral principle that applies to the issue of contraception).
In past times, the Church held the belief that the death penalty allowed society to balance the right to life for people overall. Things are different now. It’s why the institutional church is alive and why our practices can change – we don’t live in the 1st century or in the Middle Ages. We have more knowledge now and are better able to understand than many of our ancestors, therefore we can apply natural law with a different understanding. There are certainly cases where taking a life is justified. I’m a bit surprised you did not mention war (although I am certain just war theory is covered in threads under the heading of Morals)
I might suggest you read this piece by Avery Cardinal Dulles.
catholiceducation.org/articles/religion/re0461.html
Would love to hear your thoughts on Cardinal Dulles’ article.