How does something as seemingly insignificant as a condom or birth control pill lead directly to possible damnation? Let’s explore the issue for a few minutes.
An Argument from Reason
To those outside the Church, Catholic sexual teaching often seems like some backward-looking moral inhibition against human reason and modern science. Yet it is really the fullest fruit of human reason: it is in fact strengthened by a strong understanding of human biology. In fact, from a purely materialistic, utilitarian understanding of what a human being is, contraception is still wrong. Here’s one such argument:
When are things good? Things are good when they do what they’re supposed to do well (e.g., a good chair will have soft cushions). When are things bad? Things are called bad when some aspect of them undermines what they are meant to do (e.g., a bad chair has large iron spikes pointed upwards from the seat).
Biologically, what are humans supposed to do? That is, what is the biological effect of humans? It’s undeniably the same as that of any other species: self-perpetuation. Therefore, if human beings are to be good at being human beings, biologically speaking, they cannot undermine fundamental bodily functions. There may be a hierarchy of bodily functions, but even if this were granted for the sake of argument it would not change the fact that reproduction is the most important biological function for any living thing. It is a matter of life or death, and only matters of life or death can approach the weight of the biological imperative of sexuality.