2 Corinthians 12:21

When I come again (palin elqonto mou). Genitive absolute. Paul assumes it as true. Lest my God humble me (mh tapeinwsh me o qeo mou). Negative final clause (mh and first aorist active subjunctive), going back to poboumai in Ecclesiastes 20 . He means a public humiliation as his fear. The conduct of the church had been a real humiliation whether he refers to a previous visit or not. That have sinned heretofore (twn prohmarthkotwn). Genitive plural of the articular perfect active participle of proamartanw to emphasize continuance of their sinful state as opposed to mh metanohsantwn (did not repent) in the aorist tense.