correct ... reprove - rather, in the severer sense, “chastise ... punish” [Maurer].
backslidings - “apostasies”; plural, to express the number and variety of their defections. The very confederacies they entered into were the occasion of their overthrow (Pro 1:31; Isa 3:9; Hos 5:5).
know ... see - imperative for futures: Thou shalt know and see to thy cost.