Just as the death penalty for adultery appears to have been a pre-Mosiac requirement (cf. Gen. 38:24), so there is no reason to suppose that it has lost its sanction after the passing of the Mosaic economy. It reflects the unchanging justice of God.
My two cents
I didn’t realise that; I was misled into thinking that capital punishment originated with the Mosaic economy. Now I know better. Capital punishment precedes Moses.
Bahnsen, G. L. (1979). Theonomy in Christian Ethics. Nutley: Craig Press. p. 115.