What if the candidate was pro-everything else that you believe in. What if he was (example) going to save the environment, end global war, end poverty in your country, (and of course had the means to do all of these things, remember this is hypothetical). But, he is pro-choice, and that's the only thing that he/she believes in that is different from you.
Would you be so
petty as to not vote for him over one issue? I know what the pro-life and christian sites out there say. They tell you not to vote for the above candidate.
So even though you could cure world hunger, you would let millions of born children die of starvation, just to elect a pro-life candidate who may or may not even act on his pro-life opinions? He might not even achieve anything for pro-life... and he's against environmental programs, he wants to build the military and he wants to get rid of welfare... You would elect that man solely because he's pro-life? That's ridiculous.
If the first man discussed (the one who could save the world) was pro-life, I'm pro-choice and I would still vote for him. If the second man (the one who wanted to build up the military, invade china, whatever) was pro-choice, I would not vote for him.
You cannot just look at one issue that a candidate has. You must look at the whole picture. It's like not electing someone just because they have red hair. Their policies are perfect, but you have an evil ex-lover who had red hair, so you won't elect a candidate with red hair. That's how petty you seem to me.