From a parent upset that I planned to show a short abortion clip as part of my talk at his kid's high school:
“We certainly wouldn’t show images of a dead teen ejected from a vehicle crash to prove you shouldn’t drink and drive, or display a hanging person to teach against suicide; so then why show this?”
Well, we actually do show images like that, especially in the first case you mention. Consider this poster from the state of Texas, aimed specifically at students who might be tempted to drink and drive. Is this poster nothing but a “shock approach” or does it save lives?
True, graphic abortion images must be used properly (see how I carefully introduce them), meaning we should not spring them on unsuspecting audiences. When I use the short film “This is Abortion,” I tell students exactly what is in the clip and invite them to look away if they so desire. Nearly everyone watches and almost no one complains. I have found this to be true in diverse settings such as debates, banquets, schools, churches, etc. With Christian audiences, I introduce my remarks by stating Christ is eager to forgive the sin of abortion and that my purpose is not to condemn, but to clarify and equip. I use the sin of abortion to set the stage for a gospel presentation, one that offers sinners hope.