Craig Fisher recounts the time Paul uttered the words that Jesus was nearly stoned for saying:
God, perhaps himself irritated at Moses’ desire for a more useful name, says “I AM WHO I AM.” (אֶֽהְיֶ֖ה אֲשֶׁ֣ר אֶֽהְיֶ֑ה) To understand this statement, it helps to understand how others have used it in scripture. Paul, after explaining his own unworthiness, uses the same words in Greek to explain to the Corinthians his apostleship:
1Co 15:10 But by the grace of God I am what I am
Paul is saying he knows that he is not worthy of this apostleship. In his checkered past, he has persecuted Christians, but God transformed him into an apostle, preaching the good news to all who would receive him. When Paul says “I am who I am”, he means “what you see is what you get”, nothing more or less. Paul is not claiming to be an immutable, simple and incorruptible god, a claim made by leading Calvinists.
For context, click here.