Answer:
Validate them! The best thing you could do is validate that person (your coworkers) view. All because you do not agree, that does NOT give you the passage to put down those persons views. That is the worst thing you could do. That just causes conflict, and that is something we would all like to avoid. Especially in a work setting. Like politics, present your side. Don't be afraid and shy away from sharing your opinion just because your coworker doesn't agree. Voice your opinion loud and proud (and respectfully). Let them know that there are better opinion instead of abortion. Or if you are PRO abortion, then let them know why you believe it. Just make sure you stay true to yourself while remaining respectful.
Hope my advice helps! :))