It is therefore an error to judge the morality of human acts by considering only the intention that inspires them or the circumstances (environment, social pressure, duress or emergency, etc.) which supply their context. There are acts which, in and of themselves, independently of circumstances and intentions, are always gravely illicit by reason of their object; such as blasphemy and perjury, murder and adultery. One may not do evil so that good may result from it. (Catechism of the Catholic Church, no. 1756)

In any event, it is always from the truth that the dignity of conscience derives. In the case of the correct conscience, it is a question of the objective truth received by man; in the case of the erroneous conscience, it is a question of what man, mistakenly, subjectively considers to be true. It is never acceptable to confuse a ‘subjective’ error about moral good with the ‘objective’ truth rationally proposed to man in virtue of his end, or to make the moral value of an act performed with a true and correct conscience equivalent to the moral value of an act performed by following the judgment of an erroneous conscience.  It is possible that the evil done as the result of invincible ignorance or a non-culpable error of judgment may not be imputable to the agent; but even in this case it does not cease to be an evil, a disorder in relation to the truth about the good. Furthermore, a good act which is not recognized as such does not contribute to the moral growth of the person who performs it; it does not perfect him and it does not help to dispose him for the supreme good. Thus, before feeling easily justified in the name of our conscience, we should reflect on the words of the Psalm: ‘Who can discern his errors? Clear me from hidden faults’ (Ps 19:12). There are faults which we fail to see but which nevertheless remain faults, because we have refused to walk towards the light (cf. Jn 9:39-41). (John Paul II. Encyclical Veritatis splendor, no. 63, August 6, 1993)

 In order to offer rational criteria for a right moral decision, the theories mentioned above take account of the intention and consequences of human action. Certainly there is need to take into account both the intention — as Jesus forcefully insisted in clear disagreement with the scribes and Pharisees, who prescribed in great detail certain outward practices without paying attention to the heart (cf. Mk 7:20-21; Mt 15:19) — and the goods obtained and the evils avoided as a result of a particular act. Responsibility demands as much. But the consideration of these consequences, and also of intentions, is not sufficient for judging the moral quality of a concrete choice. The weighing of the goods and evils foreseeable as the consequence of an action is not an adequate method for determining whether the choice of that concrete kind of behaviour is ‘according to its species’, or ‘in itself’, morally good or bad, licit or illicit. The foreseeable consequences are part of those circumstances of the act, which, while capable of lessening the gravity of an evil act, nonetheless cannot alter its moral species. (John Paul II. Encyclical Veritatis splendor,no. 77, August 6, 1993)

Today, for an efficacious work in the field of preaching, it is necessary to understand the spiritual and psychological reality of Christians living in modern society. It is essential to realistically admit, with deep and pained sentiment, that in part, Christians today feel lost, confused, perplexed and even disillusioned; ideas conflicting with the revealed and consistently taught truth have been  widely spread; true heresies in dogmatic and moral fields have been  promoted, creating doubts, confusions, rebellions, even the Liturgy has been manipulated; immersed in the intellectual and moral ‘relativism’, and consequently permissiveness, Christians are tempted toward atheism, agnosticism, vaguely moralistic illuminism, and a sociological Christianity, without defined dogmas and without objective morality. (John Paul II. Address to the First National Conference on ‘Popular Missions during the 80s’, February 6, 1981)

In the formation of their consciences, the Christian faithful ought carefully to attend to the sacred and certain doctrine of the Church. For the Church is, by the will of Christ, the teacher of the truth. It is her duty to give utterance to, and authoritatively to teach, that truth which is Christ Himself, and also to declare and confirm by her authority those principles of the moral order which have their origins in human nature itself. Furthermore, let Christians walk in wisdom in the face of those outside, ‘in the Holy Spirit, in unaffected love, in the word of truth’ (2 Cor 6:6-7), and let them be about their task of spreading the light of life with all confidence and apostolic courage, even to the shedding of their blood. The disciple is bound by a grave obligation toward Christ, his Master, ever more fully to understand the truth received from Him, faithfully to proclaim it, and vigorously to defend it, never-be it understood-having recourse to means that are incompatible with the spirit of the Gospel. At the same time, the charity of Christ urges him to love and have prudence and patience in his dealings with those who are in error or in ignorance with regard to the faith (Paul VI. Declaration Dignitatis humanae, no. 14, December 7, 1965)

This shameful font of indifferentism gives rise to that absurd and erroneous proposition which claims that liberty of conscience must be maintained for everyone. It spreads ruin in sacred and civil affairs, though some repeat over and over again with the greatest impudence that some advantage accrues to religion from it. ‘But the death of the soul is worse than freedom of error,’ as Augustine was wont to say  (Epis. 166) When all restraints are removed by which men are kept on the narrow path of truth, their nature, which is already inclined to evil, propels them to ruin. Then truly ‘the bottomless pit’ (Rev 9:3.) is open from which John saw smoke ascending which obscured the sun, and out of which locusts flew forth to devastate the earth. Thence comes transformation of minds, corruption of youths, contempt of sacred things and holy laws — in other words, a pestilence more deadly to the state than any other. Experience shows, even from earliest times, that cities renowned for wealth, dominion, and glory perished as a result of this single evil, namely immoderate freedom of opinion, license of free speech, and desire for novelty. (Gregory XVI. Encyclical Mirari vos, August 15, 1832)

Therefore the Church announces the good tidings of salvation to those who do not believe, so that all men may know the true God and Jesus Christ whom He has sent, and may be converted from their ways, doing penance. To believers also the Church must ever preach faith and penance, she must prepare them for the sacraments, teach them to observe all that Christ has commanded , and invite them to all the works of charity, piety, and the apostolate. For all these works make it clear that Christ’s faithful, though not of this world, are to be the light of the world and to glorify the Father before men. (Vatican Council II. Sacrosanctum concilium, no. 9, December 4, 1963)

The Christian man, conformed to the likeness of that Son Who is the firstborn of many brothers, receives ‘the first-fruits of the Spirit’ (Rom. 8:23) by which he becomes capable of discharging the new law of love. (Vatican Council II, Gaudium et spes, no. 22, December 7, 1965)

Saint Paul truthfully said: ‘After a first and second warning, break off contact with a heretic, knowing that such a person is perverted and stands self-condemned.’ But they should not be counted amongst the heretics who defend their opinion, however perverse and false, without stubborn animosity, especially if this be not fruit of their own audacious presumption, but received from their parents who were seduced and induced into error, while on the other hand they seek the truth, although with circumspect care, and are disposed to correct themselves as soon as they encounter it. […] For this reason, I have written to some of the chiefs of the Donatists —  not letters of communion, which for some time they have refused to receive because of their departure from Catholic unity spread all over the world —  but rather private letters, as may be licitly sent even to pagans: even if the leaders have sometimes read them, nonetheless they did not want to, or what seems more believable, they have not been able to answer. We however think that we have, in doing this, fulfilled our duty of charity. (Saint Augustine, Epistle 43, no. 1)

For, it must be held by faith that outside the Apostolic Roman Church, no one can be saved; that this is the only ark of salvation; that he who shall not have entered therein will perish in the flood; but, on the other hand, it is necessary to hold for certain that they who labor in ignorance of the true religion, if this ignorance is invincible, are not stained by any guilt in this matter in the eyes of God. Now, in truth, who would arrogate so much to himself as to mark the limits of such an ignorance, because of the nature and variety of peoples, regions, innate dispositions, and of so many other things? For, in truth, when released from these corporeal chains ‘we shall see God as He is’ (1 John 3:2), we shall understand perfectly by how close and beautiful a bond divine mercy and justice are united; but, as long as we are on earth, weighed down by this mortal mass which blunts the soul, let us hold most firmly that, in accordance with Catholic teaching, there is ‘one God, one faith, one baptism’ [Eph. 4:5]; it is unlawful to proceed further in inquiry. Despite invincible ignorance, it is unlawful to proceed further in inquiry. (Pius IX. Allocution Singulari quadam, December 9, 1854)