A.T. Robertson Commentary John 8:24

"I said therefore unto you, that ye shall die in your sins: for except ye believe that I am [he], ye shall die in your sins." — John 8:24 (ASV)

For except ye believe (εαν γαρ μη πιστευσητε). Negative condition of third class with εαν μη and ingressive aorist active subjunctive of πιστευω, "For unless ye come to believe."

That I am he (οτ εγω ειμ). Indirect discourse, but with no word in the predicate after the copula ειμ. Jesus can mean either "that I am from above" (verse 23), "that I am the one sent from the Father or the Messiah" (7:18,28), "that I am the Light of the World" (8:12), "that I am the Deliverer from the bondage of sin" (8:28,31f.,36), "that I am" without supplying a predicate in the absolute sense as the Jews (Deuteronomy 32:39) used the language of Jehovah (cf. Isaiah 43:10 where the very words occur ινα πιστευσητε--οτ εγω ειμ). The phrase εγω ειμ occurs three times here (8:24,28,58) and also in 13:19. Jesus seems to claim absolute divine being as in 8:58.