I think this line of thought is dangerous, as it could easily be used to justify abortion. Better to die in the womb than be raised in an unbelieving household.
Arguing with unbeleivers about anything other than the condition of THEIR soul and the Way, the Truth and the Life ( Jesus) is a waste of time.
They thrive on contention, explaining to them the mind of God ( as if we can) is a fools errand. Tell them the Gospel of Grace ( the only one) and them tell them that now they have had fair warning, their blood is on them and them alone; they are one breathe or heart beat from meeting the Creator and that there is no redo or mulligans once before the throne...
Hand them a business card with your contact info for possible future reference, “Drop the mike” and leave them to their reveling.