"Whether you vote for the lesser of two evils, you vote for evil" is a phrase that is thrown around during campaign season, usually to criticize people who support a candidate from one of the major parties, because the other major party candidate is an even worse choice. It is used to advocate for either minor party candidates, or for a complete boycott of the political system.
One of the difficulties with this phrase is that "evil" can mean two things. The phrase "lesser of two evils" is a legal term for choosing the better of two bad options. However, "evil" can be used to mean something radically morally wrong. One of the problems of the phrase is that it seems to conflate the two, saying that by voting for a less unfavorable choice of candidate, you are advocating the "demonic" brand of evil.
And here, after two decades of hearing the phrase, I realized a very easy, very important rejoinder to it: because someone doesn't agree with me, it doesn't mean they are evil. I can support a candidate who I have disagreements with on any number of issues, because the fact that they hold a different opinion than me (or, as the case often is, downplay their actual opinions to better deal with the general electorate), doesn't mean that they are evil. Even if they are stupid or unreasonable, it doesn't mean they are evil. In fact, I would go even further. A candidate can be corrupt, immoral or lacking in empathy, and they are still not capital-E "Evil".
At some level, I do feel I become morally complicit by supporting candidates whose political beliefs are outside of my definitions of morality. But I don't believe that every candidate who doesn't share every single belief of mine is "Evil", because if I believed such a thing, I would be dooming about 95% of my fellow citizens to the realm of "Evil".