Recently Tory MP Stephen Woodworth from Kitchener made a motion in the Canadian Parliament to examine the wording of section 223 of the Canadian Criminal Code. As it currently stands, a foetus is not considered human until it exits the mother’s womb as a child. If Mr. Woodworth’s wording were to go through, a foetus would be considered human from the moment of conception, granting it full protection under the Canadian Criminal Code and thus closing the loophole that currently allows legal abortions in Canada. (There is no law in Canada permitting abortions, nor is there one outlawing abortion either). You can read Mr. Woodworth's proposal here.
The Catholic Church has always known that abortion goes against God’s natural law. In fact, the Catholic Catechism states:
From its conception, the child has the right to life. Direct abortion, that is, abortion willed as an end or as a means, is a "criminal" practice, gravely contrary to the moral law. The Church imposes the canonical penalty of excommunication for this crime against human life.
This Catholic teaching is based in sacred scripture:
Before I formed you in the womb I knew you, and before you were born I consecrated you (Jer. 1:5)
Unfortunately, quoting scripture and the catechism won’t convince a pro-choice lobbyist. Taking a logical approach should allow you to bring them to the Catholic Church’s original conclusion that life begins at conception.
If they believe that human life begins only at birth, then ask your pro-choice adversary to distinguish between a baby that is 5 minutes old and a foetus that is 5 minutes away from being born. If there is none, then what is the difference between 5 minutes before birth and 10? If there is still no difference, then continue asking in increments of hours, days, weeks and then months. Since the child’s growth in the womb is as natural as their growth outside of the womb, there really is no point, except conception, where one can say that the child has finally become human.
Humanity begins at conception.
Confirm, then, your belief in the sanctity of life through scripture and doctrine, but convince your adversaries with the logic they love to use to support their own arguments.