Human. If failing God’s vision for being human made one subhuman... then Nugent and everyone else on this mortal coil would be subhuman in that sense, making the term superfluous.
That said, it was clearly figurative, and mongrel seems to have been meant in the sense of dog, not the sense of mixed race. A clarification could have been in order.
How do you clarify the truth my friend? by “turning your cheek and let whomever slap you in the face again????