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".
Source: Veritatis Splendor (Vatican.va)