Tim Keller recently wrote an op-ed in the NY Times explaining how Christian ethics do not line up neatly with the Republican/Democrat divide. He rightly argued that the Christian’s ultimate allegiance is to God’s kingdom of love and justice, which both transcends and subordinates mainstream politics. However, Keller did not explore why even anti-Trump Christians who embrace his liminal perspective on politics continue to vote primarily for a single party: Republicans.

The reason is abortion. While concerns about liberal views on sexuality/gender, identity politics, religious liberty, and the role of the state are also important, abortion remains the issue for many Christian voters. Evangelical Christians believe abortion is murder, so the thousands of elective abortions performed every day outweigh the moral weaknesses of the Republican platform. Like such Christians, I believe the pro-life cause is of the highest importance, but the Republican Party under Trump has proven itself morally unfit to represent the movement. The longer the Republican Party is the face of the pro-life movement, the more credibility the movement will lose. As a result, the time has come for pro-life Christians to vote against the Republican Party.

Christians claim that an unborn baby has rights because it is created in the image of God, knitted together in the mother’s womb by God himself. Who are we to undo the creative act of God, who has lent us our very existence? By connecting the pro-life argument to an act of God himself, Christians are appealing to an objective moral reality that transcends cultures. Human life is sacred by divine fiat, not because “We the People” consent to such a principle.

By contrast, in a culture that has drunk deeply from the font of moral relativism, many Americans believe themselves to be the ultimate arbiters of good and evil. We let each other do what we want, as long as it doesn’t hurt someone else. And since unborn babies cannot be reliably identified as “persons” (so goes the argument), they have no rights to be abrogated, and the mother can do as she pleases.

Democrats tend to hold this latter view, and conservatives rightly identify it as a deeply dangerous tenet, not merely for pro-lifers. Subjective morality, untethered from external principles, can easily become a self-justifying means for oppression. One need only look at college campuses to see how the idea of tolerance, distorted by subjectivism, is used as a weapon to suppress speech and even incite mobs to physical abuse.

Despite their many failings, Republicans have tended towards a view of the world that accepted certain objective moral standards, and objective reality more broadly. That is, until Donald Trump, who clearly has no time for anything objective. First there was the birther conspiracy, then after his election the denials of Russian interference, the ever-changing story of his affair with Stormy Daniels, the shifting stances on border separations to appease the public, and even his sad attempt to rewrite the history of inauguration crowd sizes, to mention only a few.

Despite what he may say, Trump clearly views “truth” as a tool to be manipulated for political expediency and personal prestige. His actions contravene the content of Christian teaching and deny the existence of objective truth on a daily basis, from science to economics to war to ethics. And if he does not believe in the necessary underpinnings of the pro-life movement, surely he cannot be its champion.

But Trump is just one man. Before long he will be gone, and Republicans will once again represent the pro-life cause with integrity, right?

I doubt it. Republicans have gone out of their way to appease the base by kowtowing to the worst of Trump. And it is not that they have merely overlooked small errors here or there, which could be expected of any party. Rather, Republicans have presided over the destruction of their own cherished institutions. Not only have they ignored Trump’s constant stream (nay, flood) of lies, they have stood idly by as Trump takes a sledge hammer to alliances, the press, the intelligence community, the idea of individual dignity, and the rule of law.

No such party—with a head of blatant immorality and a body of cowardice and complicity—can ever hope to win the protracted struggle against abortion or any other moral argument. Moral authority is required to speak to such an issue, and even if the courts overturn Roe, conservatives will lose the battle against abortion if the pro-life movement is hitched to a party that has no moral standing. A court ruling may last a generation, but the real battle is within the culture, where hearts and minds must be won by the power of moral integrity and the conviction of conscience.

Core elements of modern liberalism are deeply antithetical to orthodox Christianity, and I believe the rift will only widen. But the Republican Party has also rendered itself incapable of advocating for important Christian causes. If the pro-life movement and other moral concerns are to be adequately represented, Christians must reject the Republican Party and seek to establish a legitimate conservative voice. If Christians continue to support the Republican Party as the lesser of two evils, the pro-life cause will collapse under the weight of its own moral contradictions.