I suppose a lot depends on the situation, and the question of what our message actually conveys.
To take an extreme example, if you've got a young woman who finds herself pregnant and just isn't ready to be a mother. She doesn't really want an abortion but doesn't see much option, so she goes to the clinic. As she approaches she has a load of people getting in her face telling her abortion is murder, shouting at her, maybe showing her graphic images and calling her a babykiller and so on. Then she gets inside and meets someone who calms her down, assures her everything will be OK, and they can help her take care of her problems. The people outside shouting can't realistically be surprised that she ignores their message and listens to the one she's given inside.
If the same people outside were to talk to her more rationally, try to walk with her and explain why they think abortion is wrong, maybe have someone who considered an abortion and is now very happy to be a mother, maybe putting her in contact with places that can support her through the pregnancy and help with either raising the child or, if she so chooses, giving it up for adoption for a family that can't have children, maybe she would be more likely to listen.
Ultimately if our message could be summarized as ".... and then you'll go to hell and then you'll be sorry" the chances are we might as well not bother saying it because people are unlikely to listen to it. Even Jesus saved his more cutting remarks for the religious leaders of the day - how often did Jesus use the "brood of vipers" kind of remark when dealing with the tax collector and prostitutes?
