Here’s an unpopular opinion for you: Using birth control is wrong. Pursuing sexual activity and pleasure while intentionally avoiding sexual fruitfulness is wrong. The fact that using some form of birth control is a normal practice even among Christians has no relevance for its morality. What God has joined together, let no man separate. He has joined together man’s greatest responsibility in this world with man’s greatest pleasure in this world. That is cause for gratitude, not for creative dissection.
And that opinion is not inherently Roman Catholic. Read this from Calvin, commenting on Genesis 38:
“And the thing which he did displeased the LORD. Less neatly the Jews speak about this matter. I will contend myself with briefly mentioning this, as far as the sense of shame allows to discuss it. It is a horrible thing to pour out seed besides the intercourse of man and woman. Deliberately avoiding the intercourse, so that the seed drops on the ground, is double horrible. For this means that one quenches the hope of his family, and kills the son, which could be expected, before he is born. This wickedness is now as severely as is possible condemned by the Spirit, through Moses, that Onan, as it were, through a violent and untimely birth, tore away the seed of his brother out the womb, and as cruel as shamefully has thrown on the earth. Moreover he thus has, as much as was in his power, tried to destroy a part of the human race. When a woman in some way drives away the seed out the womb, through aids, then this is rightly seen as an unforgivable crime. Onan was guilty of a similar crime, by defiling the earth with his seed, so that Tamar would not receive a future inheritor.”