If you do something that the Roman Catholic teaches is a grave matter, but you don't agree it is a grave matter, do you have to confess it?

Dialogue with Confessor

This is an extremely difficult question, and therefore you should probably explain the situation to your confessor. The doctor-patient analogy is often used for confession. Ideally you want to disclose all possible wounds to the doctor, even if you do not believe they are sinful, and even if you ultimately disagree with the doctor about treatment. The dialogue with the doctor is still important. A good confessor will not refuse absolution if you are sincere. Confession is supposed to be a dialogue between the penitent and the confessor:

The first form makes possible a highlighting of the more personal- and essential-aspects which are included in the penitential process. The dialogue between penitent and confessor, the sum of the elements used (the biblical texts, the choice of the forms of "satisfaction," etc.), make the sacramental celebration correspond more closely to the concrete situation of the penitent. The value of these elements are perceived when one considers the different reasons that bring a Christian to sacramental penance: a need for personal reconciliation and readmission to friendship with God by regaining the grace lost by sin; a need to check one's spiritual progress and sometimes a need for a more accurate discernment of one's vocation; on many other occasions a need and a desire to escape from a state of spiritual apathy and religious crisis. Thanks then to its individual character, the first form of celebration makes it possible to link the sacrament of penance with something which is different but readily linked with it: I am referring to spiritual direction. So it is certainly true that personal decision and commitment are clearly signified and promoted in this first form.

-Reconciliation and Penance, 32

Thomas Aquinas

With that in mind, the first thing to note is that the justification of sinners requires a movement towards God and a movement away from sin. In confessing your sins, then, you would have to be opposed to sin wherever it is found. You would have to be open to the possibility that contraception is sinful, and you would have to essentially say to yourself, "If I am mistaken and I become convicted that contraception is sinful, then I will consequently reject it."

And therefore just as by the movement of the free will toward God the person who is justified is disposed to obtain grace, so also by the motion of the free will against sin he must be disposed to the expulsion of guilt. [...] But in the justification by which the impious are justified, there must be two dispositions: one for introducing grace, namely, the movement of the free will toward God; and the other for expelling guilt, namely, the movement of the free will against sin.

-Aquinas, Super Sententiarum, lib. 4, d. 17, q. 1, a. 3, qc. 4, resp.

The second thing to note is that you should not confess what you do not believe to be a sin, for this is a form of deception. Instead you should explain to your confessor that you have committed acts which the Church holds to be sinful but which you do not hold to be sinful. Confession is a manifesting of one's conscience, and since contraception is not held in your conscience you cannot confess it honestly. Nevertheless, you must remain open to the possibility that your conscience is improperly formed, and that it is not recognizing what is in fact a sin.

. . . confession [...] conveys by its very name a revealing of something that someone holds in his conscience, for in this way the mouth and heart come together in one. For if someone utters with his mouth something that he does not hold in his heart, it is not called a confession but a deception.

-Aquinas, Super Sententiarum, lib. 4, d. 17, q. 3, a. 2, qc. 2, resp.

Third, is the confession valid? In my estimation the confession would be valid because--so long as you are sincere--the non-disclosure of contraception would be a venial sin, and would probably not be the kind of venial sin that invalidates a confession. Like I said, the best thing to do is to enter into dialogue with the confessor about the predicament (and to perhaps find a single confessor who can learn your story and guide you forward).

The venial sin that does not impede penance does not impede the remission of mortal sin, which happens through penance.

-Aquinas, Super Sententiarum, lib. 4, d. 16, q. 4, a. 1, qc. 3, ad1

If you do something that the Roman Catholic teaches is a grave matter, but you don't agree it is a grave matter, do you have to confess it?

The short answer is yes: One must confess such sins.

Just like G. K. Chesterton said, “I don’t need a church to tell me I’m wrong where I already know I’m wrong; I need a Church to tell me I’m wrong where I think I’m right.”

What is sin and what sins need to be confessed in the Sacrament of Penance?

Sin is an offense against God that ruptures our communion with Him and with His Church (CCC 1440).

It is far more than “breaking the rules,” but is a failure to love God and to love others, which causes real damage in all our relationships.

There are sins totally incompatible with love for God and others (mortal sins, in which genuine love is “dead”), and ones in which love is less grievously wounded (venial or “easily forgiven”).

The Church says that all grave or mortal sins must be confessed as soon as possible (CIC 988).

The Catholic Church can not error, according to the Catholic Faith and under the teachings by the Sovereign Pontiff and the Teaching Magisterium of the Church, in the matter of faith and morals. This has been the constant teaching of the Church.

Just because one does not agree with what the Church teaches as grave matter, gives them a a get out of jail free card.

In such situations, individuals commit a sin of pride against docility to the teaching authority of the Church. In a lesser degree, some individuals might be guilty of having a misinformed conscience.

Grave matter remains grave matter in the eyes of the Church.

Notwithstanding, sometimes there are extenuating circumstances that can mitigate the gravity of a sin. But to commit a sin because one does not agree with the Church changes nothing. The sin must be confessed. This must be done before going to communion at mass.

To be a Catholic in good standing, there are rules that must be obeyed.

That the Church is infallible in her definitions on faith and morals is itself a Catholic dogma, which, although it was formulated ecumenically for the first time in the Vatican Council, had been explicitly taught long before and had been assumed from the very beginning without question down to the time of the Protestant Reformation. The teaching of the Vatican Council is to be found in Session III, cap. 4, where it is declared that "the doctrine of faith, which God has revealed, has not been proposed as a philosophical discovery to be improved upon by human talent, but has been committed as a Divine deposit to the spouse of Christ, to be faithfully guarded and infallibly interpreted by her"; and in Session IV, cap. 4, where it is defined that the Roman pontiff when he teaches ex cathedra "enjoys, by reason of the Divine assistance promised to him in blessed Peter, that infallibility with which the Divine Redeemer wished His Church to be endowed in defining doctrine regarding faith and morals". Even the Vatican Council, it will be seen, only introduces the general dogma of the Church's infallibility as distinct from that of the pope obliquely and indirectly, following in this respect the traditional usage according to which the dogma is assumed as an implicate of ecumenical magisterial authority. Instances of this will be given below and from these it will appear that, though the word infallibility as a technical term hardly occurs at all in the early councils or in the Fathers, the thing signified by it was understood and believed in and acted upon from the beginning. We shall confine our attention in this section to the general question, reserving the doctrine of papal infallibility for special treatment. - Proof of the Church's infallibility

If one does not agree that something is grave matter, do you have to confess it? Yes! Just because one does not think that murder is serious matter, does not make it acceptable to deliberately not confess (conceal it from the confessor) it in confession.

As far as artificial contraception is concerned it it considered serious matter and is intrinsically evil and sinful.

The Catholic position on contraception was formally explained and expressed by Pope Paul VI's Humanae vitae in 1968. Artificial contraception is considered intrinsically evil, but methods of natural family planning may be used, as they do not usurp the natural way of conception.

In justification of this position, Pope Paul VI said:

Responsible men can become more deeply convinced of the truth of the doctrine laid down by the Church on this issue if they reflect on the consequences of methods and plans for artificial birth control. Let them first consider how easily this course of action could open wide the way for marital infidelity and a general lowering of moral standards. Not much experience is needed to be fully aware of human weakness and to understand that human beings—and especially the young, who are so exposed to temptation—need incentives to keep the moral law, and it is an evil thing to make it easy for them to break that law. Another effect that gives cause for alarm is that a man who grows accustomed to the use of contraceptive methods may forget the reverence due to a woman, and, disregarding her physical and emotional equilibrium, reduce her to being a mere instrument for the satisfaction of his own desires, no longer considering her as his partner whom he should surround with care and affection.

On July 17, 1994, John Paul II clarified the church's position during a meditation said prior to an angelus recitation:

Unfortunately, Catholic thought is often misunderstood ... as if the Church supported an ideology of fertility at all costs, urging married couples to procreate indiscriminately and without thought for the future. But one need only study the pronouncements of the Magisterium to know that this is not so. Truly, in begetting life the spouses fulfill one of the highest dimensions of their calling: they are God's co-workers. Precisely for this reason they must have an extremely responsible attitude. In deciding whether or not to have a child, they must not be motivated by selfishness or carelessness, but by a prudent, conscious generosity that weighs the possibilities and circumstances, and especially gives priority to the welfare of the unborn child. Therefore, when there is a reason not to procreate, this choice is permissible and may even be necessary. However, there remains the duty of carrying it out with criteria and methods that respect the total truth of the marital act in its unitive and procreative dimension, as wisely regulated by nature itself in its biological rhythms. One can comply with them and use them to advantage, but they cannot be "violated" by artificial interference.

In 1997, the Vatican's Pontifical Council for the Family stated:

The Church has always taught the intrinsic evil of contraception, that is, of every marital act intentionally rendered unfruitful. This teaching is to be held as definitive and irreformable. Contra­ception is gravely opposed to marital chastity; it is contrary to the good of the transmission of life (the procreative aspect of matrimony), and to the reciprocal self-giving of the spouses (the unitive aspect of matrimony); it harms true love and denies the sovereign role of God in the transmission of human life.

Christian views on birth control