Just this morning, I came across again these powerful passages in John Paul II's Veritatis Splendor, paragraph #102-105 regarding the difficult situations in morality and our need to choose the truth with the help of God's grace, and that no commandment is too burdensome with God's help. I have added emphasis to certain passages, which make the points that need to be made in such arguments against the choosing of lesser evil. Since I am in the middle of doing some work, I won't offer more reflections of my own at this point; maybe later. I encourage you to read these sections if you haven't, and if you have read Veritatis Splendor, please take a moment to re-read these sections. You can find the whole encyclical here.
102. Even in the most difficult situations man must respect the norm of morality so that he can be obedient to God's holy commandment and consistent with his own dignity as a person. Certainly, maintaining a harmony between freedom and truth occasionally demands uncommon sacrifices, and must be won at a high price: it can even involve martyrdom. But, as universal and daily experience demonstrates, man is tempted to break that harmony: "I do not do what I want, but I do the very thing I hate... I do not do the good I want, but the evil I do not want" (Rom 7:15, 19).
What is the ultimate source of this inner division of man? His history of sin begins when he no longer acknowledges the Lord as his Creator and himself wishes to be the one who determines, with complete independence, what is good and what is evil. "You will be like God, knowing good and evil" (Gen 3:5): this was the first temptation, and it is echoed in all the other temptations to which man is more easily inclined to yield as a result of the original Fall.
But temptations can be overcome, sins can be avoided, because together with the commandments the Lord gives us the possibility of keeping them: "His eyes are on those who fear him, and he knows every deed of man. He has not commanded any one to be ungodly, and he has not given any one permission to sin" (Sir 15:19-20). Keeping God's law in particular situations can be difficult, extremely difficult, but it is never impossible. This is the constant teaching of the Church's tradition, and was expressed by the Council of Trent: "But no one, however much justified, ought to consider himself exempt from the observance of the commandments, nor should he employ that rash statement, forbidden by the Fathers under anathema, that the commandments of God are impossible of observance by one who is justified. For God does not command the impossible, but in commanding he admonishes you to do what you can and to pray for what you cannot, and he gives his aid to enable you. His commandments are not burdensome (cf. 1 Jn 5:3); his yoke is easy and his burden light (cf. Mt 11:30)."
103. Man always has before him the spiritual horizon of hope, thanks to the help of divine grace and with the cooperation of human freedom.
It is in the saving Cross of Jesus, in the gift of the Holy Spirit, in the Sacraments which flow forth from the pierced side of the Redeemer (cf. Jn 19:34), that believers find the grace and the strength always to keep God's holy law, even amid the gravest of hardships. As Saint Andrew of Crete observes, the law itself "was enlivened by grace and made to serve it in a harmonious and fruitful combination. Each element preserved its characteristics without change or confusion. In a divine manner, he turned what could be burdensome and tyrannical into what is easy to bear and a source of freedom".
Only in the mystery of Christ's Redemption do we discover the "concrete" possibilities of man. "It would be a very serious error to conclude... that the Church's teaching is essentially only an "ideal" which must then be adapted, proportioned, graduated to the so-called concrete possibilities of man, according to a "balancing of the goods in question". But what are the "concrete possibilities of man" ? And of which man are we speaking? Of man dominated by lust or of man redeemed by Christ? This is what is at stake: the reality of Christ's redemption. Christ has redeemed us! This means that he has given us the possibility of realizing the entire truth of our being; he has set our freedom free from the domination of concupiscence. And if redeemed man still sins, this is not due to an imperfection of Christ's redemptive act, but to man's will not to avail himself of the grace which flows from that act. God's command is of course proportioned to man's capabilities; but to the capabilities of the man to whom the Holy Spirit has been given; of the man who, though he has fallen into sin, can always obtain pardon and enjoy the presence of the Holy Spirit".
104. In this context, appropriate allowance is made both for God's mercy towards the sinner who converts and for the understanding of human weakness. Such understanding never means compromising and falsifying the standard of good and evil in order to adapt it to particular circumstances. It is quite human for the sinner to acknowledge his weakness and to ask mercy for his failings; what is unacceptable is the attitude of one who makes his own weakness the criterion of the truth about the good, so that he can feel self-justified, without even the need to have recourse to God and his mercy. An attitude of this sort corrupts the morality of society as a whole, since it encourages doubt about the objectivity of the moral law in general and a rejection of the absoluteness of moral prohibitions regarding specific human acts, and it ends up by confusing all judgments about values.
Instead, we should take to heart the message of the Gospel parable of the Pharisee and the tax collector (cf. Lk 18:9-14). The tax collector might possibly have had some justification for the sins he committed, such as to diminish his responsibility. But his prayer does not dwell on such justifications, but rather on his own unworthiness before God's infinite holiness: "God, be merciful to me a sinner! " (Lk 18:13). The Pharisee, on the other hand, is self-justified, finding some excuse for each of his failings. Here we encounter two different attitudes of the moral conscience of man in every age. The tax collector represents a "repentant" conscience, fully aware of the frailty of its own nature and seeing in its own failings, whatever their subjective justifications, a confirmation of its need for redemption. The Pharisee represents a "self-satisfied" conscience, under the illusion that it is able to observe the law without the help of grace and convinced that it does not need mercy.
105. All people must take great care not to allow themselves to be tainted by the attitude of the Pharisee, which would seek to eliminate awareness of one's own limits and of one's own sin. In our own day this attitude is expressed particularly in the attempt to adapt the moral norm to one's own capacities and personal interests, and even in the rejection of the very idea of a norm. Accepting, on the other hand, the "disproportion" between the law and human ability (that is, the capacity of the moral forces of man left to himself) kindles the desire for grace and prepares one to receive it. "Who will deliver me from this body of death?" asks the Apostle Paul. And in an outburst of joy and gratitude he replies: "Thanks be to God through Jesus Christ our Lord! " (Rom 7:24-25).
We find the same awareness in the following prayer of Saint Ambrose of Milan: "What then is man, if you do not visit him? Remember, Lord, that you have made me as one who is weak, that you formed me from dust. How can I stand, if you do not constantly look upon me, to strengthen this clay, so that my strength may proceed from your face? When you hide your face, all grows weak (Ps 104:29): if you turn to look at me, woe is me! You have nothing to see in me but the stain of my crimes; there is no gain either in being abandoned or in being seen, because when we are seen, we offend you. Still, we can imagine that God does not reject those he sees, because he purifies those upon whom he gazes. Before him burns a fire capable of consuming our guilt (cf. Joel 2:3)".