JOHN 8:58 does not necessarily mean what it seems
"Jesus said unto them, "truly I say to you, before Abraham was, I am". (RSV).
This scripture is routinely compared to Exodus 3:14, where we read of Yahweh: "God said unto Moses, "I AM WHO I AM". And he said "Say this to the people of Israel, "I AM has sent me to you"". (RSV).
Just a few notes: The Exodus statement was made in response to a request from Moses for God to identify himself. And the reply (understandably?) "I am who I am" is simply impatient. I believe that I myself have at times said "I am who I am" in response to certain challenges. And the second part, "I am has sent me", just carries on the impatience of God with Moses's request for identification. But God gives in to Moses in the next verse and identifies himself as "Yahweh", the traditional god of the Hebrews. So while the theologians have made much of this passage, it is hardly the claim to uniqueness that they often assert. It just shows that the Hebrew god was a rather human figure who got impatient with people not knowing who he was -- and who handed out carved stone tablets and various other things.
Moving on to John 8:58 and the expression "I am" there: The Greek expression Jesus used here is "Ego eimi" -- which is the first person singular form of the verb "to be" in Greek. Its meaning is not however as straightforward in Greek as it is in its English counterpart. It is quite imprecise and can be translated in a number of ways. Even in that particular passage, translators differ on their rendering of it. Some authorities suggest "I have been" but the suggestion I like best is "I am he". That translation fits the text best, it seems to me. He was, after all, answering the enquiry, "Have you seen Abraham?". And in other passages of the NT (e.g. John 14:9) "eimi" is routinely translated as "have been".
So Jesus was certainly claiming to be an ancient being but the statements in Exodus and John are clearly not comparable. And in fact the case and tense structures of Hebrew and Greek are very different so any exact comparability would in any event be fanciful.
What Jesus actually said in his native Aramaic, we can only guess of course. We have only John's report in Greek.
For what it is worth, John would have been well aware of the ancient and widely used translation of the Hebrew scriptures into Greek -- The Septuagint -- and the Septuagint renders Exodus 3:14 as “EGO EIMI HO OHN,” meaning “I am the being” or "I am the one", so again comparability between the two texts is lost. If John had seen Jesus's Aramaic words as a reference to Exodus 3:14, he would presumably have translated them into Greek in the same way that the ancient Jewish translators behind the Septuagint did.
That John in fact chose a Greek expression that is capable of at least two different meaings is however well in keeping with his Gnostic tendencies. Gnosticism (the pretence of secret knowledge) was around long before Christ and it did eventually infect Christianity. There were various gnostic Christian sects from the second century on. John, however, does appear to have written quite late in the first century so may perhaps be regarded as the first of the Christian Gnostics. The book of Revelations, in particular, reads very much like a Gnostic text, with its constant use of symbolism.
So John took advantage of the various uses of "eimi" to make one of his Gnostic utterances. Compare John 1:1, where his clever use of an anarthrous predicate also leads most Greekless people into thinking he is saying more than he is. He was obviously a very competent Greek stylist.
So John was not being deceitful in using the the words he did. He was just being vague -- perhaps with the aim of saying that REAL Christians would be able to untangle the intended meaning, which is a very Gnostic thing to do. And at the time that was probably no difficulty. But with the impossibility of exactly translating all Greek tenses into languages with different verb structures, misunderstandings have certainly developed.
As someone who has often battled with translating German into English (which are after all two closely related languages) I am confident in saying in fact that ALL translations are only approximations. I comment on that at greater length here. On some occasions you do have to study the original texts to get an accurate sense of the passage.
I can't resist adding a few more comments about the Septuagint. The Torah section of it (including Exodus) is quite ancient and the oldest surviving manuscripts of the OT are in fact mostly of the Septuagint. And there are quite a few places where the Septuagint and the Masoretic (Hebrew) text differ in meaning, though the differences are not usually greatly important.
It used to be automatic among Bible translators to prefer the Masoretic renderings and dismiss the Septuagint as "freely" translated. A widely held view among textual scholars these days, however, holds that the Septuagint was based on a pre-Masoretic version of the Hebrew text and that its renderings are therefore at least as likely to represent the lost original texts as are the Masoretic renderings. In which case the less enigmatic Septuagint rendering of Exodus 3:14 might reasonably be preferred. So YHWH might originally have been recorded as saying not "I am who I am" but rather something like “I am the being” or "I am the one".
Note finally that the apostle Paul normally quoted from the Septuagint in his epistles. How's that for a headspinner?
I would think that in the circumstances a really serious Christian Bible student (are there any left?) would be heading out to buy himself a copy of the Septuagint with an accompanying English translation. I do myself own such a volume but it is quite old so I doubt that it is still in print anywhere. For what it is worth, however, it was published by Samuel Bagster and Sons of London in 1879. Bagster had a most comprehensive range of Bible study aids but with the decline of Biblical scholarship they have now gone out of business. There is however a translation only here that sounds useful. The most "official" translation of the Septuagint at the moment is here but I don't like the assumptions underlying it at all at all.