I think trying to appeal to divine authority is unlikely to get you far with a group of people who reject divine authority.

I'm not sure why people get religious about this. The far more interesting approach is to try to use reason along side other current laws to determine the answer to two questions - what defines a human life, and when is it acceptable to take one? For example, trying to compare things like medical support for preterm babies to medical support of coma patients to investigate the logic behind viable fetuses vs various life support methods, etc.

A similar interesting situation is how in some cases murdering a pregnant woman counts as a double homicide because the law includes the unborn child

You didn’t answer my question.

You said that people who are against abortion have no right to say other people can’t get abortions.

By what authority do you declare them to have no right? The UN wrote a document and is humanity’s moral conscience? Yourself and your own head?

I didn't say anything; I'm not the person you were replying to. But I will say that I suspect your arguments that God has the authority over a document people wrote is, again, unlikely to find an audience among those who don't think He exists.