I oppose abortion, and so do you. Here's how I know that you know it is wrong to kill a human being not yet born. Here's the scenario - you see a woman who you know to be pregnant. She's smoking. Let's be honest, we all agree she shouldn't be smoking in her "condition" because it will harm the child. I have even heard people express their belief that their should be a law against smoking when pregnant, and around children.
OK, let's add some context to the scenario. She's smoking on the way to an abortion clinic for a procedure. Is it OK to harm the child with cigarette smoke now?
I rest my case. This isn't arguing apples and oranges, this is life and death, this is right and wrong, this is good and evil.