Without understanding (ασυνετους). Same word in verse Romans 1:21.
Covenant-breakers (ασυνθετους). Another paronomasia or pun. Α privative and verbal συνθετος from συντιθημ, to put together. Old word, common in LXX (Jeremiah 3:7), men "false to their engagements" (Sanday and Headlam), who treat covenants as "a scrap of paper."
Without natural affection (αστοργους). Late word, α privative and στοργη, love of kindred. In N.T. only here and 2. Timothy 3:3.
Unmerciful (ανελεημονας). From α privative and ελεημων, merciful. Late word, only here in N.T. Some MSS. add ασπονδους, implacable, from 2. Timothy 3:3. It is a terrible picture of the effects of sin on the lives of men and women. The late Dr. R. H. Graves of Canton, China, said that a Chinaman who got hold of this chapter declared that Paul could not have written it, but only a modern missionary who had been to China. It is drawn to the life because Paul knew Pagan Graeco-Roman civilization.