I invite you to comment on a hypothetical situation: a man, Fred, is married to a woman who has a sexually transmitted disease which does not respond to medication. He uses a condom with the intention of preventing the virus responsible for the disease from infection him. If his wife did not have the virus, he would not wear the condom. His intention is not to contracept, but to prevent the spread of disease. The contraceptive effect is an unintended side-effect.
Now I understand that this is not what the Church teaches. But I fail to see the logic. Can anyone explain it to me, when the situation of a woman using oral contraception to protect against acne, or to regulate periods is acceptable to the Church, as the contraceptive effect is an unintended side effect.
To understand both situations, one must first understand why the Church abhors contraceptives. The Church believes that sex is first and foremost an act of procreation. To interfere with it is to interfere with the the whole objective of sex - procreation. The moment that this procreative element is removed, sex becomes nothing more than an act of self-gratifying pleasure, exploited for the sake of giving oneself selfish pleasure without the opportunity of the creation of life. Contraceptives are thus condemned because they enable this to happen. The actual sin committed is recreational sex, and not strictly the use of substances that can be contraceptives.
With this in mind, let us tackle the second situation first. It is acceptable for women (or men, if there were such a medical indication) to take an oestrogen-and-progresterone pill for the purpose of therapy - be it as vain as acne control or as serious as cancer prophylaxis - so long as they do not knowingly and willingly engage in sex while they are using it. So long as they remain chaste, there is no sex that the pill will interfere with, and so there is no recreational sex. However, if she decides to have sex with her husband while still using the pill, she has committed a sin. Even though the initial intention of taking the pill was therapeutic, she knows that the pill would prevent her from conceiving, and yet she decided to have sex. Thus it can be easily concluded that she had no intention of having sex for the purpose of procreation - it was merely recreational. Thus, it is a sin. If the husband was aware of this and yet continued to have sex, then he is party to the sin too.
Now, back to the first situation - a man wishes to wear a condom to avoid contracting a incurable sexually-transmitted disease from his wife. However, condoms do not prevent the transmission of sexually-transmitted diseases by simply being worn on the penis - they prevent the transmission of sexually-transmitted diseases
during sex. Why does he want to have sex then, if he knows that condoms are contraceptive? It is clearly not for procreative reasons. It is not explicitly mentioned in your analogy, but it is clear that if he wanted to have children (and I hardly think it wise to have a child when your wife is carrying an incurable sexually transmitted disease), he wouldn’t be so eager to have sex with a condom on.
Contrary to what you think, the Church does not consider the condom itself evil. In fact, if it were possible for condoms to have a therapeutic use, then the same rules would apply to it as to the pill - it can be used for therapeutic purposes so long as the user abstains from sex. However, this is not the case in the analogy you gave. Instead, it is the fact that the condom is being used to have sex without procreation that is the evil inherent in the system.
You have set up a false dilemma by forcing us to choose whether he has to use a condom or not at all - why can’t he just not have sex? Is it so hard? Why is it so necessary for him to have sex? Is he or his wife going to die without it? Sometimes, I wonder if the only reason why there has been so much confusion is because modern society has forgotten the meaning of sex. People appear to assume sex is a necessary expression of love within a loving couple, to which children are merely incidental or optional. Basically, “We don’t really need children, but we simply must have sex.” If that is so, then they are sorely mistaken. Sex is not just some pleasurable activity. It is a great act between a committed husband and wife that creates life - and it should not be anything but that.
