Who was attacking Paul's apostleship and what exactly did they accuse him of?
The Judaizing Jews attacked Paul's apostleship, accusing him of being an imposter who invented his commission. They claimed he lacked any badge of authority or letters of commendation, and could not claim to have walked with Jesus three years like Peter, James, and John.
Les explains that Paul had to defend his apostleship, as he was under constant attack, especially from the Judaizing Jews. They accused him of being an imposter who had drummed it all up himself, that he had no badge of authority or letters of commendation, and that he could not claim to have walked with Jesus three years like Peter, James, and John. Later in the chapter they also say his letters are weighty, but his presence is weak.