Oh, but it matters totally whether our convictions against abortion are based ultimately upon our believe about the immortality of the fetus. For if our position based on this conviction, then our convictions about freedom of conscience come into play. I am arguing within the Catholic community about what our own beliefs compel us to do on this question (and only on this question). 

We both see very clearly that it would be a violation of the conscience of others where we required that other accept our convictions about immortality. Since we  have no right to demand that other agree with us on this point, and since our anti-abortion position presupposes immortality, then when we push for laws outlawing abortions (which we do), we are violating our own principles. 

He has nothing to do with our civil rights to engage in the public sphere along with everyone else. In is an internal matter of our own conscience obliging us to refrain. Abortion is an error, but error has rights.