Here are further errors I came across in Mounce's Grammar. They occur in Chapter 16, headed "Present Active Indicative," page 130, under "Exegetical Insight."
After mentioning a number of passages in which ἐγώ εἰμι occurs in the NT in relation to Jesus, the writer goes on to say
There is more. Jesus' use of ἐγώ εἰμι harks back to the Old Testament, to the story of Moses when he was approached by God at the burning bush (Exod 3). When Moses challenged to Lord to give his name, God replied by saying (in the Septuagint) eg ἐγώ εἰμι ὁ ὤν ("I am the one who is"). That is, Yahweh is the great "I AM" (Exod 3:14). Jesus taps into this famous title for God when he says to the Jews, "Before Abraham was, I am (ἐγώ εἰμι)" (John 8:58), ascribing to himself the very name that Yahweh used in the Old Testament concerning himself. And this same name and expression underlie all of Jesus' ἐγώ εἰμι statements in John's Gospel.
It is amazing to see such exegetical nonsense in a book teaching basic Biblical Greek grammar. There are the following three errors in the passage quoted above.
1. The Greek form of the divine name is actually ὁ ὤν, not ἐγώ εἰμι.
אֶהְיֶה אֲשֶׁר אֶהְיֶה in Exodus 3:14 is rendered ἐγώ εἰμι ὁ ὤν in the Septuagint, in which ὁ ὤν represents the Greek form of the divine name, not ἐγώ εἰμι, which are simply the subject and the linking verb of the sentence respectively. This is confirmed later in the same verse by the words addressed to Moses: ὁ ὢν ἀπέσταλκέ με πρὸς ὑμᾶς. The New Testament further confirms this in Revelation 1:8, where God again describes himself as ὁ ὢν, not ἐγώ εἰμι.
2. In πρὶν Ἀβραὰμ γενέσθαι ἐγὼ εἰμί (John 8:58), ἐγὼ εἰμί means simply "I have existed." Jesus affirms his existence in some form before Abraham was born. This truth is affirmed also in Colossians 1:17: καὶ αὐτός ἐστιν πρὸ πάντων.
The parallelism between John 8:58 and Colossians 1:17 is clearly seen when the two are juxtaposed with the word order of the latter rearranged:
πρὶν Ἀβραὰμ γενέσθαι ἐγὼ εἰμί
πρὸ πάντων αὐτός ἐστιν.
3. The statement "And this same name and expression underlie all of Jesus' ἐγὼ εἰμί statements in John's Gospel" is demonstrably false. For example, in Ἐγώ εἰμι τὸ φῶς τοῦ κόσμου, Ἐγώ εἰμι is simply the subject and the verb of the sentence respectively, with τὸ φῶς τοῦ κόσμου as the complement. In the case of Ἐγώ εἰμι without an expressed complement, as in Mark 14:62, it is just a matter of supplying the approprite complement (Ἐγώ εἰμι the Christ in Mark 14:62). In Mark 13:6 and Luke 21:8, we have false Christs claiming Ἐγώ εἰμι, i.e., "I am the Christ." This is confirmed by the parallel in Matthew 24:5: Ἐγώ εἰμι ὁ χριστός. Even the blind man in John 9:9 says, Ἐγώ εἰμι ("I am he").