Rom 1:31

“"Without natural affection, implacable." For this Christ Himself also pronounces to be the cause of wickedness, saying, "When iniquity shall abound, the love of many shall wax cold." (Matt. xxiv. 12). This too St. Paul here says, calling them "covenant-breakers, without natural affection, implacable, unmerciful," and showing that they were traitors even to the gift of nature. For we have a sort of family feeling even by nature towards one another, which even beasts have got towards each other. "For every beast," it says, "loveth his like, and every man his neighbor." (Ecclus. xiii. 15.) But these became more ferocious even than they. The disorder then which resulted to the world by evil doctrines, he proves to us by these witnesses, and clearly shows that the malady in either case came of the negligence of them that were disordered. He shows besides, what he did in the case of the doctrines, that they were here also deprived of all excuse...”

“Without understanding,.... Of God, of his nature and worship, of things divine and even moral, being given up to a reprobate mind: covenant breakers; had no regard to private or public contracts: without natural affection; to their parents, children, relations and friends: implacable; when once offended there was no reconciling of them: unmerciful; had no pity and compassion to persons in distress.”

“Without understanding - Ασυνετους, from α, negative, and συνετος, knowing; persons incapable of comprehending what was spoken; destitute of capacity for spiritual things. Covenant-breakers - Ασυνθετους, from α, negative, and συντιθημυι, to make an agreement; persons who could be bound by no oath, because, properly speaking, they had no God to witness or avenge their misconduct. As every covenant, or agreement, is made as in the presence of God, so he that opposes the being and doctrine of God is incapable of being bound by any covenant; he can give no pledge for his conduct. Without natural affection - Αστοργους; without that attachment which nature teaches the young of all animals to have to their mothers, and the mothers to have for their young. The heathens, in general, have made no scruple to expose the children they did not think proper to bring up, and to despatch their parents when they were grown old or past labor. Implacable - Ασπονδους, from α, negative; and σπονδη, A Libation. It was customary among all nations to pour out wine as a libation to their gods, when making a treaty. This was done to appease the angry gods, and reconcile them to the contracting parties. The word here shows a deadly enmity; the highest pitch of an unforgiving spirit; in a word, persons who would not make reconciliation either to God or man. Unmerciful - Ανελεημονας; those who were incapable, through the deep-rooted wickedness of their own nature, of showing mercy to an enemy when brought under their power, or doing any thing for the necessitous, from the principle of benevolence or commiseration.”