Archaic KJV Word
Damnable
Modern equivalent: destructive
What Was Lost
The eternal stakes. 'Damnable heresies' were not merely bad ideas or annoying teachings but beliefs that would destroy souls for eternity. The word was a fire alarm about false doctrine. When damnable became a casual curse, the Church lost a word that communicated 'this teaching will cost you everything, forever.'
Closest Survivor in Modern English
damnation (still carries theological weight when used precisely)
Peak Usage (1611)
KJV 2 Peter 2:1 -- 'Who privily shall bring in damnable heresies'
Died ~1900 (shifted from theological to colloquial intensifier)
Weakened from 'worthy of eternal damnation/leading to the destruction of the soul' to a mild curse word ('damnable weather'), trivializing a word about eternal judgment into casual frustration.
What Replaced It
“destructive”
Physical; damnable meant eternally destructive to the soul, not merely harmful
“condemned”
Legal; damnable carried the cosmic weight of divine judgment, not courtroom sentencing
“accursed”
Archaic but closer; damnable specifically meant 'this will damn you -- destroy your soul forever'