I think that most people who practice it don't really know what the Church teaches about it, they only know what they have been TOLD why the Church teaches it and that is because the Church is an ancient institution stuck in the past. Most people will never really understand why until they have a true conversion of heart to do the right thing. OR until they are told by pastoral authority.
A few months ago, my daughter had her first reconcilliation retreat. My sil, on my husband's side's son is in the same class. So we were at the retreat together. This is a new priest in our parish. At the retreat he talked to the parents about reconcilliation. He said it was important for parents to practice it and he also said that purgatory and hell were real. He did not say it in those blunt of terms. But anyway, for years before the priests in that parish never said anything like that.
After that at a family gathering, my sil TOLD me she was convicted, because she'd NOT heard a priest talk like that in a LONG time. And her husband told me later it had been bothering her all day.
So, she KNEW it was real--the potentials upon death--she'd just not heard it emphasized by a pastoral authority--- and it really really bothered her. To the point where she said she didn't like the priest.
But see, that's just internal conviction. Her heart, knowing what is right, and coming to terms with it.
Anyways, my point is, uncomfortability with the truth is usually conviction and that is where it starts. And usually there is some resistance there.
In dealing with birth control, our culture has told us it's right, and we have not heard that it's wrong. So naturally when people hear it's wrong, they will resist.
Michelle