It is difficult to know why Paul’s letter prior to 1 Corinthians was not Scripture. Would we have a 28th book to the Bible if it were ever found? Theoretically, yes. Providentially, no. If this letter did not make it to us, then God must not have meant us to have it. Therefore, perhaps this letter was not inspired Scripture. Instead, it was just a personal letter, unlike the rest of his letters (1 Cor. 14:37; 1 Thess. 2:13; 2 Pet. 3:15-16).