The NIV translated this as accursed brood
(see also Isaiah 57:4; Ephesians 2:3; Ephesians 5:8; 1 Peter 1:14). The simple meaning of the phrase is that these heretics are subject to divine judgment (cursing, see also Deuteronomy 11:28–29; Deuteronomy 28:15, Deuteronomy 28:45; Deuteronomy 29:27; Proverbs 3:33; Galatians 3:10, Galatians 3:13; Hebrews 6:8; James 3:10). The verdict which they denied is upon them.1
14 They have eyes full of adultery, insatiable for sin. They entice unsteady souls. They have hearts trained in greed. Accursed children!