How do you respond to the Church as Christs Church on earth and the Jewish scripture and legal authorities, all unanimous in condemnation of the death penalty today despite it being supposedly ‘commanded’ by Scripture. People who are claiming to have more expertise than the most recognised authorities on Scripture, need to prove some sort of alternate God given authority.
‘Jesus answered them, "Is it not written in your law, `I said, you are gods’? If he called them gods to whom the word of God came (and scripture cannot be broken)’ (John 10: 34-35).
I would respond by just telling them to read the Bible which we believe to be the inspired word of God. The Bible itself, both the Old and New Testaments including Jesus, testifies that the revealed Law of the Old Covenant was given by God to the Israelites through Moses. The Church has always taught this and still does naturally (cf. CCC#1961). It appears from modern biblical scholarship that some various precepts of the Law other than the Decalogue seem to have pre-existed the Sinai Covenant in a similar form among various ancient Semitic peoples and may have been inserted into the Sinaitic ‘Book of the Covenant’ by Moses through God’s command and counsel and thus ratified and sanctioned by Him , for the entire Old Law of the Israelites is presented in the Bible as coming from God through Moses in the context of the events of Sinai.
As far as the view that is held today among the Catholic Church and the Jewish state of Israel concerning the death penalty, this is a different issue than the Old Testament Law of the ancient Israelites. Your claim that the Jewish state and all Jewish scholars today are unanimous in their condemnation of the death penalty is probably questionable unless you can provide some evidence. I recently read an article on a poll taken from the Jewish population in Israel which was fairly recent I believe and something like 33% said they were in favor of the death penalty. At any rate, Christians are not obligated to believe whatever present day Jews believe concerning the death penalty. And, sadly, they have extremely serious interpretative problems with the Old Testament in the person of Jesus Christ, the promised Messiah, who alone is the fulfillment of the Old Testament. Still, I feel very close to the Jewish people as Jesus, Mary, St Joseph, and the apostles were Hebrews and all the prophets, and Abraham, Isaac, Jacob, David.
At least presently, the entire body of the Catholic faithful, clergy and lay, is not entirely unanimous concerning the new teaching in the catechism on the death penalty. There are some catholic vocal critics and possibly many who are silent. And imo, we ought not be to quick to condemn those catholics who may have some misgivings about the new wording in the catechism which is only about two months old or so. I think they have reasonable misgivings and questions as I do myself not in the least of an unexpectant overnight conversion from essentially 2000 years of Church Tradition and of 1400 years of biblical teaching in the Old Testament prior to the coming of Christ.