The Catechism of the Catholic Church does not forbid capital punishment.
False. The Catechism is very explicit (and correct)
As long as you can lock someone away, the Catechism does not support execution. Critical reading is of critical importance for critical understanding, dear friend. The Catholic church does not condone killing except in extremis as the last and only resort left.
And even this is an innovation (of St. Augustine's) that was never accepted in the East. The early Church did not allow any killing under any circumstance, even when justified!
This includes +Justin Martyr (100-165 AD), Dialogue with Trypho 110, where he says their swords were changed into ploughs. And in his Apology 1.39, where he says
The same sentiment comes from +Clement of Alexandria (150- c. 211 AD) who writes
Above all, Christians are not allowed to correct with violence the delinquencies of sins, Fragments: Maximus, Sermon 55
In our case, murder being once for all forbidden, we may not destroy even the ftus in the womb, Apology 9
Shall it be held lawful to make an occupation of the sword, when the Lord proclaims that he who uses the sword shall perish by the sword? And shall the son of peace take part in the battle when it does not become him even to sue at law? And shall he apply the chain, and the prison, and the torture, and the punishment, who is not the avenger even of his own wrongs? The Chaplet 11
Athenagoras of Athens (c 180 AD)
We cannot endure even to see a man put to death, though justly, A Plea for the Christians 35
Origen of Alexandria (185-254 AD) writes
And as we by our prayers vanquish all demons who stir up war, and lead to the violation of oaths, and disturb the peace, we in this way are much more helpful to the kings than those who go into the field to fight for them And none fight better for the king than we do. We do not indeed fight under him, although he require it; but we fight on his behalf, forming a special army an army of piety by offering our prayers to God, Against Celsus 8.73
Cyprian of Carthage (250 AD)
The whole world is wet with mutual blood; and murder, which in the case of an individual is admitted to be a crime, is called a virtue when it is committed wholesale. Impunity is claimed for the wicked deeds, not on the plea that they are guiltless, but because the cruelty is perpetrated on a grand scale, Epistle 1.6
Athanasius of Alexandria (296-373 AD) says
And this is at least incredible, inasmuch as even now those Barbarians who have an innate savagery of manners . . . and cannot endure to be a single hour without weapons; but when they hear the teaching of Christ, straightway instead of fighting they turn to husbandry, and instead of arming their hands with weapons they raise them in prayer, and in a word, in place of fighting among themselves henceforth they arm against the devil and against evil spirits, subduing these by self-restrains and virtue of soul. Now this is at once a proof of the divinity of the Saviour, since what men could not learn among idols they have learned from him, On the Incarnation of the Word 52.2-4
This is what the early Church believed. There is no such thing as acceptable killing. The problem I encounter with many Catholics is that everything they know seems to come from the superficial reading of the Catechism, never mind the Fathers. If the Church followed what seems to be the American Catholic mind set Kolo was addressing, the Church would would have had no martyrs and no saints who died without lifting a finger, imitating the Lord to the very end, but a whole bunch of Jewish-like rebels who fought to the end.