The Magisterium has many times taught that contraception is intrinsically evil. The use of contraception is a type of act that is inherently ordered toward an evil end, toward the deprivation of the procreative meaning of sexual relations. The knowing choice of any type of act that is inherently ordered toward this evil end is a grave sin; it is an intrinsically evil act.
No circumstance or purpose can ever make the use of contraception licit, since this type of act is intrinsically illicit, and therefore contrary to the unchanging eternal moral law of God. The use of contraception is not justified by a non-contraceptive intention, nor by a medical purpose, nor by a dire circumstance, nor by being used outside of marriage. The use of contraception is not morally neutral. The use of contraception is not only immoral within marriage.
The evil moral object of contraception is the deprivation of the procreative meaning from sexual acts. All intrinsically evil acts, in order to be actual sins, must be knowingly chosen (i.e. intentionally chosen, deliberately chosen). But this does not imply that your intention can make the use of contraception somehow not intrinsically evil, or not truly contraceptive. The intentional choice of an inherently disordered type of act is always immoral.
My writings on this topic:
Intrinsic Evil and the Moral Object – this article explains the three fonts of morality, and the basic concepts of moral object and intrinsic evil.
And here is a set of articles refuting common false doctrinal errors on the topic of contraception. Many of these errors are so thoroughly contrary to the infallible teaching of the ordinary and universal Magisterium that the errors rise to the level of heresy.
Contraception and Heresy – Part 1 – The More Common Heresies
Contraception and Heresy – Part 2 – On the Use of Contraception Outside of Marriage
Contraception and Heresy – Part 3 – On the Latin text of Humanae Vitae
Contraception and Heresy – Part 4 – The Moral Object of Contraception
Contraception and Heresy – Part 5 – Contra Jeff Mirus on Contraception
And here are two more articles, this time refuting the errors of Jimmy Akin, first on what makes an act intrinsically evil, and second on contraception as an intrinsically evil act.
Intrinsic Evil versus Proportionalism – A refutation of Jimmy Akin’s heretical errors on intrinsic evil and the moral object.
Modern Heresies on Contraception – A refutation of Jimmy Akin’s heretical errors on contraception and marriage.
I have also written several blog posts on this subject:
my blog post index
I was going to write yet another lengthy article or post on this subject, but that would be repetitious.
Errors on this topic continue to spread among the faithful, esp. online. The same false ideas, already refuted by myself and other faithful Catholics, are proposed and even taught, again and again. No matter how many times the Magisterium teaches on this subject, no matter in how many different ways, there are innumerable persons offering clever misinterpretations in order to nullify or distort that clear, universal, and infallible teaching.