Anyhow, given that, while the Church’s position that the death penalty is a proper penalty under some circumstances, finds it self in an era when those circumstances virtually never arise…
Your posts are always the epitome of quote mining. Reading the section in full with regards to Aquinas’ words gives much more clarity… In answer to the question Whether vengeance should be wrought by means of punishments customary among men? He responds…
"These punishments are fixed by the divine law as appears from what we have said above (I-II, 105, 2).
I answer that,
Vengeance is lawful and virtuous so far as it tends to the prevention of evil. Now some who are not influenced by motive of virtue are prevented from committing sin, through fear of losing those things which they love more than those they obtain by sinning, else fear would be no restraint to sin. Consequently vengeance for sin should be taken by depriving a man of what he loves most. Now the things which man loves most are life, bodily safety, his own freedom, and external goods such as riches, his country and his good name. Wherefore, according to Augustine’s reckoning (De Civ. Dei xxi), “Tully writes that the laws recognize eight kinds of punishment”: namely, “death,” whereby man is deprived of life; “stripes,” “retaliation,” or the loss of eye for eye, whereby man forfeits his bodily safety; “slavery,” and “imprisonment,” whereby he is deprived of freedom; “exile” whereby he is banished from his country; “fines,” whereby he is mulcted in his riches; “ignominy,” whereby he loses his good name.
Our Lord forbids the uprooting of the cockle, when there is fear lest the wheat be uprooted together with it. But sometimes the wicked can be uprooted by death, not only without danger, but even with great profit, to the good. Wherefore in such a case the punishment of death may be inflicted on sinners.
All who sin mortally are deserving of eternal death, as regards future retribution, which is in accordance with the truth of the divine judgment. But the punishments of this life are more of a medicinal character; wherefore the punishment of death is inflicted on those sins alone which conduce to the grave undoing of others.
The very fact that the punishment, whether of death or of any kind that is fearsome to man, is made known at the same time as the sin, makes man’s will avers to sin: because the fear of punishment is greater than the enticement of the example of sin."
So while clearly we are aware that “all sin deserves punishment” according to divine justice… the punishments of this life must conform to our human capacity to wrought justice. Through Christ we know that to love God we must love each other. Human justice conforms to the requirements of the common good.