Moral absolutism and specifically the NAP is based on an axiomatic belief that peaceful interaction is always preferable to violent interaction.
I can't convince someone to accept this belief.
If someone accepts this belief, morality follows logically.
If someone rejects this belief and instead believes violence is always or even sometimes preferable to peace, then that person is choosing to live in under the law of the jungle aka might makes right, which is amoral.
Moral absolutism and NAP is the only moral theory that is non-contradictory and internally consistent logically.
This also assumes one is interested in defining a logically consistent morality, which they may not be.