Pacos Pete, the Catholic Catechism teaches that one must confess his or her sins before taking the Eucharist in Mass. Since the Eucharist is central to Mass, your acquaintance went to confession to purify her soul, so that her body would not reject the living body and blood of Jesus Christ.
This soldier’s Catholic associate is uninformed about the nature of God’s forgiveness. God will forgive the soldier an infinite number of times, provided that the soldier’s repentance is sincere, and that he follows the instructions of his confessor, such as praying the Rosary or making another act of true contrition. God expects us to sin repeatedly; he also expects us to try to do better but if we fail again, he is ready to forgive us again. This is the unbounded mercy and generosity of God, in action.
Continued:
In the third place, it is not my intention to explain here at length how the occupation and work of a soldier is in itself right and godly because I have written quite enough about that in my book Temporal Authority: To What Extent It Should Be Obeyed.3 Indeed, I might boast here that not since the time of the apostles have the temporal sword and temporal government been so clearly described or so highly praised as by me. Even my enemies must admit this, but the reward, honor, and thanks that I have earned by it are to have my doctrine called seditious and condemned as resistance to rulers.4 God be praised for that! For the very fact that the sword has been instituted by God to punish the evil, protect the good, and preserve peace [Rom. 13:1–4; I Pet. 2:13–14] is powerful and sufficient proof that war and killing along with all the things that accompany wartime and martial law have been instituted by God. What else is war but the punishment of wrong and evil? Why does anyone go to war, except because he desires peace and obedience?
Now slaying and robbing do not seem to be works of love. A simple man therefore does not think it is a Christian thing to do. In truth, however, even this is a work of love. For example, a good doctor sometimes finds so serious and terrible a sickness that he must amputate or destroy a hand, foot, ear, eye, to save the body. Looking at it from the point of view of the organ that he amputates, he appears to be a cruel and merciless man; but looking at it from the point of view of the body, which the doctor wants to save, he is a fine and true man and does a good and Christian work, as far as the work itself is concerned. In the same way, when I think of a soldier fulfilling his office by punishing the wicked, killing the wicked, and creating so much misery, it seems an un-Christian work completely contrary to Christian love. But when I think of how it protects the good and keeps and preserves wife and child, house and farm, property, and honor and peace, then I see how precious and godly this work is; and I observe that it amputates a leg or a hand, so that the whole body may not perish. For if the sword were not on guard to preserve peace, everything in the world would be ruined because of lack of peace. Therefore, such a war is only a very brief lack of peace that prevents an everlasting and immeasurable lack of peace, a small misfortune that prevents a great misfortune.
What men write about war, saying that it is a great plague, is all true. But they should also consider how great the plague is that war prevents. If people were good and wanted to keep peace, war would be the greatest plague on earth. But what are you going to do about the fact that people will not keep the peace, but rob, steal, kill, outrage women and children, and take away property and honor? The small lack of peace called war or the sword must set a limit to this universal, worldwide lack of peace which would destroy everyone.
This is why God honors the sword so highly that he says that he himself has instituted it [Rom. 13:1] and does not want men to say or think that they have invented it or instituted it. For the hand that wields this sword and kills with it is not man’s hand, but God’s; and it is not man, but God, who hangs, tortures, beheads, kills, and fights. All these are God’s works and judgments.
To sum it up, we must, in thinking about a soldier’s office, not concentrate on the killing, burning, striking, hitting, seizing, etc. This is what children with their limited and restricted vision see when they regard a doctor as a sawbones who amputates, but do not see that he does this only to save the whole body. So, too, we must look at the office of the soldier, or the sword, with the eyes of an adult and see why this office slays and acts so cruelly. Then it will prove itself to be an office which, in itself, is godly and as needful and useful to the world as eating and drinking or any other work.
Luther, Martin: Pelikan, Jaroslav Jan (Hrsg.) ; Oswald, Hilton C. (Hrsg.) ; Lehmann, Helmut T. (Hrsg.): Luther’s Works, Vol. 46 : The Christian in Society III. Philadelphia : Fortress Press, 1999, c1967 (Luther’s Works 46), S. 46:93-97