What if the state were to decide that I don't have the right to self-defense? Without natural rights in what way could I argue that this is immoral? If I don't have natural rights then I don't have the right to my life or my property and I have no argument.
If the state did so then the state would probably eventually fall. The state can and should circumscribe the laws on self-defence for good reasons, but to abolish that right would be detrimental to everyone. The point is that the state can effectively abolish self-defence if it wished, whether someone argues it's a natural right or a social right won't make a whit of difference.
Now how does the state go about abolishing that which it has no means to advance, control, or take?
Again... the anti-theist confuses the RIGHT, with the means to exercise the Right... and government protections which prevent government power from usurping those rights.
Where a government fails to defend the means of the individual to exercise their unalienable rights, that government is a direct, clear and present danger to the individual... and will eventually be destroyed by the individual.
Such is the case with the perpetual failure of Europe and Australia's chronic ne'erdowell status.