Ramesh Ponnuru is a fellow at the American Enterprise Institute and a columnist for Bloomberg Opinion. Robert P. George is the McCormick Professor of Jurisprudence at Princeton University.

Joe Biden is only the second baptized Catholic president of the United States, and the first since abortion became a central issue in our politics. The Catholic Church’s opposition to the deliberate killing of unborn children is both firm and well-known. But Biden supports an almost unlimited right to abortion and federal funding for it. That juxtaposition is renewing the debate about the moral obligations of conscientious Catholic citizens, including public officials.

News stories have heralded the rebirth under Biden of a politically liberal version of Christianity that places more emphasis on such issues as poverty and immigration than on sexual morality. Catholic bishops have reportedly been divided over how to respond.

It is a moment for Catholics, laity and clergy alike, to be clear about what the church teaches. Catholicism is quite capacious: It has room for many political tendencies. A Catholic may in good conscience believe that the federal government must do more to regulate markets to serve the common good, or that excessive regulation has contributed to poverty and should be relaxed, or something in between. The catechism instructs that “more prosperous nations are obliged, to the extent they are able, to welcome the foreigner in search of the security and the means of livelihood which he cannot find in his country of origin.” What that means in practice for U.S. policy is, however, something on which equally faithful Catholics may reasonably disagree.

Nothing, then, is in principle wrong with liberal and conservative Catholics making themselves heard as distinct voices. But Catholic teaching imposes limits on what policies can be supported. No Catholic should, for example, approve a policy that leads to the routine and large-scale separation of children from their parents in the name of combating illegal immigration. Indeed, Catholics are called to oppose any such policy. To the extent we fail in this duty — because of partisanship, timidity, hardness of heart or some other reason — we fall short of what our faith demands.

So it is with abortion. Biden is among those Catholics who have contributed to confusion on this point. He has said his faith teaches that human life begins at conception and declared, “I accept it in my personal life.” But he will not “impose it” on others. Yet it is science, not any catechism, that teaches us that at conception a new and distinct member of the species Homo sapiens comes to be. What the Catholic Church adds is that we have a solemn obligation to do what we can to see to it that justice is done to all human beings — including those at the earliest developmental stages. (Catholics are, of course, and thankfully, not alone in seeing this imperative.)

Abortion is, in the church’s view, not just immoral in the way it is to take the Lord’s name in vain or to commit adultery. It is not in itself a matter of sexual ethics. It is a grave injustice in the same way it is to perform any act designed to kill an innocent human being. Laws allowing it, or treating it as a right, are gravely unjust, too, in the same way that it would be unjust for laws to allow the deliberate killing of any other innocent human beings, especially on a mass scale. Pope Francis has for this reason appealed to “all politicians, regardless of their faith convictions, to treat the defense of the lives of those who are about to be born and enter into society as the cornerstone of the common good.”

Biden, however observant he may be in other respects, does not accept the church’s teaching on this subject. He flagrantly rejects it. He may sincerely wish that nobody would ever procure or perform an abortion, and in that sense be “personally opposed” to it. He nonetheless favors excluding a particular class of human beings from the same protection against homicide that he favors for everyone else. He speaks in favor of that injustice, and he works to further it.

Nothing in the church’s teaching on abortion implies that it is the only issue that ought to concern Catholic citizens and officials. Nor does it preclude working with the Biden administration on initiatives that seem likely to promote the general welfare, or commending it when deserved. We are, however, obligated to tell the truth about abortion and what the church actually teaches about it: to tell it to our fellow Catholics, and to everyone else. We owe it to the unborn. We owe it to our fellow citizens of a nation committed to “justice for all.” And we owe it, as well, to President Biden himself, who on this issue is guilty of profound injustice.

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