Libertarians—many of whom are not religious, let alone Catholic—often refer to human freedom as being rooted in the idea of self-ownership; that men have control over their own bodies—and by extension—the products of their labor. An atheist can hardly invoke God or the Church to defend his right to run his own life—that is, the right of an individual as the owner of his life and body. The Christian will rightly object that we do not own ourselves; we were created by God and are held in being by Him.
In addition to owing God for our very existence, there is that matter of the forbidden fruit and our first parents. Even if we had owned ourselves at the start—which we did not—man sinned and lost what he had been given. We forfeited paradise though sin. So God—already owning the ground and every creature that walked there—stepped into history as a man and paid the price to buy us back from sin. Scripture is crystal clear on this matter:
“Do you not know that your body is a temple of the Holy Spirit within you, which you have from God? You are not your own; you were bought with a price. So glorify God in your body.”
1 Corinthians 6:19-20
No Christian can claim ownership of himself, but the responsibility is still his. We are stewards of our own lives, bodies and goods. [CCC 952] We answer to God for ourselves and how we have conducted our lives. Other men will answer for their actions.
Whether we hold our own bodies as stewards or whether we mistakenly believe our bodies to be ours alone, all “have dominion over their actions through their free-will.” [ST, I-II Q 1, A 2.]
Catholics freely choose to be subject to God and His Church and live their lives (some more, some less) accordingly. On judgment day, we answer to God, not to some busybody or policeman on our street.