Christians cannot unjustly destroy or support those who unjustly destroy the image of God, even if it is done in the name of protecting and defending the image of God. Good ends, no matter how noble, do not excuse evil means. Christ’s gospel does not free us to become worldly pragmatists or even spiritual utilitarians. Consequentialism is not Christian liberty. God cares about the way in which we do justice and show steadfast love to our neighbors (Micah 6:8). Any politician that runs on a platform of death in the name of human flourishing is one for whom a believer should never cast their vote.
To be clear, I am not saying that being good on a single issue (like abortion) would be enough to qualify a person for leadership who is otherwise incompetent. However, compromising on a particularly weighty issue is enough to disqualify a person who is otherwise very competent.