Opposing evil and doing good are essential obligations

"Some argue that we should not focus on policies that provide help for pregnant women, but just focus on the essential task of establishing legal protections for children in the womb. Others argue that providing lifeaffirming support for pregnant women should be our only focus and this should take the place of efforts to establish legal protections for unborn children. We want to be clear that neither argument is consistent with Catholic teaching. Our faith requires us to oppose abortion on demand and to provide help to mothers facing challenging pregnancies."
U.S. Conference of Catholic Bishops

"Barack Obama and John McCain differ on many important issues about which reasonable people of goodwill, including pro-life Americans of every faith, disagree: how best to fight international terrorism, how to restore economic growth and prosperity, how to distribute the tax burden and reduce poverty, etc.

But on abortion and the industrial creation of embryos for destructive research, there is a profound difference of moral principle, not just prudence. These questions reveal the character and judgment of each man. Barack Obama is deeply committed to the belief that members of an entire class of human beings have no rights that others must respect."
Robert P. George, McCormick Professor of Jurisprudence and Director of the James Madison Program in American Ideals and Institutions, Princeton University