I really don’t want to debate but I will try to make my point Natural law drives everyone even non believers. No-conscience evil people are not the norm even if they do occasionally try to take over the world. The gospel is for Christians I happen to follow it myself
Gospel believers learn to transcend even the approximations of natural law. Their life is now governed by special supervision of Christ.
The attempt to blur the two is one made by many churches.
I.e. to just tell a society to “rest on natural law” is to actually cheat it of the possibility of gospel progress.
People may have a dim apprehension of God that we CALL “natural law” but that doesn’t make it the ultimate rule.
And I know you said you “don’t want to debate” but to try to come to the most exact understanding of the situation possible is incumbent upon all of us. Inexact understandings will mislead us.
We can appeal to the kind of dim consciousness of God that is called “natural law” but even that varies in intensity and spectrum in different peoples. The moment it is set up as some kind of rule in its own self... as though it could self exist the way gospel does... is the moment we attempt to embrace a nebula. All manner of argument can and will be made about its specifics, for that reason. Nothing can substitute for genuine gospel witness.
So let us of course persuade a society through whatever light we can shed upon it that abortion is wrong, and then thank the Lord when it is thus persuaded. However we must not rest. This is only a witness in itself to something greater.
Just because a particular denomination has reified a nebulous concept doesn’t mean that it can stand alone.