Theological Question: If there is no God, can there be such a thing as "Justice"?

I’m listening to the latest Season of Someone Knows Something and David Ridgen respectfully says that he is an athirst, but believes in the adage, “the truth will set you free.” I guess my theological question would be, if there is no God, can there be such a thing as justice?

And if God is what gives our lives meaning/value (which I do), how can one say that taking another’s life is unjust?

This is not a personal attack on David Ridgen, as I think he is great! He genuinely cares about individuals (as well as animals) and has a beautiful way of communicating with people.

If anyone would like to explain how justice matters in a world where God does not exist, I think this would make for a good discussion?