One of the arguments that Republicans are having among ourselves is what do we do if Donald Trump is the Republican nominee in November? Some argue that they must support the party's nominee, but others (commentator Erick Erickson, for example), take the position that they cannot vote for Trump. Taking the latter position leads those who say vote for the nominee to make the accusation that failure to vote for Trump-the-nominee constitutes making a positive choice in favor of Hillary Clinton or Bernie Sanders, and therefore moral responsibility for the negative impact of the election of one of those hard-left candidates. I would argue that those who make such arguments are wrong not merely as to the question of intent, but also as to the moral implications of that choice.
It is a fundamental tenet of traditional Christian moral teaching that one may not choose to commit an objectively immoral (malum in se) act. If an act is gravely and objectively morally evil, one cannot do it, even if the result of doing it might be good or better than the alternative. For example, it is not permissible to kill a wealthy man simply because doing so will result in an immediate bequest to a local charity which will allow it to remain open and continue to do good works for thousands of needy people. Similarly, one may not rob a bank or sexually abuse a child because of a hostage taker has threatened to kill an innocent person if you do not. The Christian -- indeed, any person is morally obligated not to choose to do evil and to reject the utilitarian notion that choosing objective evil is morally acceptable if the ultimate outcome is a subjectively (or even objectively) greater good.
Which leads us to the electoral question. When approaching the ballot box, one has the obligation to vote in a manner that is objectively moral. In most elections, this is an easy task, for there is usually at least one non-corrupt candidate whose positions and promises are, if not perfect, within the realm of moral acceptability. If there is more than one acceptable candidate, it is acceptable to vote for any one of them -- though the more virtuous act is to vote for the greater good. If there is not such a candidate, it is the obligation of a moral person to abstain from voting for any candidate a vote for the lesser evil is still a choice to do evil, and the choice to do evil is always objectively wrong. The utilitarian argument that one should choose the lesser evil must be rejected.
Which leads us to the potential situation facing voters in November of 2016. Hillary Clinton, the likely Democrat candidate, is personally corrupt and is running on a platform that highlights her support for abortion and laws that would deeply infringe upon freedom of speech, freedom of the press, freedom of religion, the right to keep and bear arms, and the property rights of Americans. Her Democrat opponent, Bernie Sanders, is a socialist whose program is steeped in Marxist ideology and will require confiscatory levels of taxation that will reduce most Americans to the position of being wards of the state rather than free and self-sufficient citizens, not to mention the fact that he is every bit as hostile to constitutional liberties as his Democrat rival. Ordinarily, this would make a vote for the Republican alternative the only good moral choice except for the fact that Donald Trump may be that nominee.
Why can't a Christian --- or any individual with a functioning moral compass vote for Donald Trump? That's easy Trump combines the hostility to freedom displayed by both Democrats with Hillary's personal corruption and Bernie's totalitarian tendencies. Add to that a thin-skin and personal vindictiveness that rivals the character flaws of Barack Obama and you have a perfect storm of political evil. Many commentators not just on the Left, but also on the Right have called Trump a fascist. And even if most scholars of fascism are unwilling to go quite so far as labeling him a fascist, they so note his the we and rhetoric do sound many themes that have been a part of fascist rhetoric and platforms from the beginning of that malignant movement. At a bare minimum, it is fair to label Trump a proto-fascist. On that basis alone, it is morally unacceptable to vote for him, because the racism, support for violence against opponents, and efforts to intimidate and control the press are objective evils which we cannot legitimately support.
So what is a voter with a right conscience to do? Civic participation and voting in elections are generally seen as virtuous things, but choosing to vote for evil is never an acceptable alternative. That is true even when one might vote for what one views as the lesser of two evils, for that still constitutes the material cooperation in evil. (Note, please, that this differs from voting for a candidate whose platform is not 100% in line with ones principles in that case one is voting for a good but flawed candidate because a perfect one does not exist.) One is compelled to abstain from voting for either candidate in such an instance whether by leaving that race blank on the ballot or by voting for a third-party or independent candidate. While the outcome will still advance evil, one's refusal to give active assent by giving a vote to an evil candidate absolves one of that evil and does not constitute a so not omission. It is, in fact, the only morally acceptable choice for one not wedded morally relativistic utilitarianism.