Did Peter fully understand Paul's gospel when he wrote near the end of his ministry?
No, Peter did not fully comprehend Paul's gospel even near the end of his ministry. According to 2 Peter 3, although Paul's gospel had been on the scene many years, Peter still had not really got the full knowledge of it. He understood enough to acknowledge that the Lord's long-suffering is salvation.
Les explains that 2 Peter 3:15 is a loaded verse that is seldom referenced. He notes that Peter wrote near the end of his ministry, just shortly before he was martyred. Paul's gospel had been on the scene a good many years. Even though Peter had a hard time comprehending it at the beginning, he still hadn't really got the full knowledge of it. But he had at least enough to tell us that the long-suffering of our Lord is salvation, which Les says is the whole theme of the Book.
And account that the longsuffering of our Lord is salvation; even as our beloved brother Paul also according to the wisdom given unto him hath written unto you;
More Questions
How much of Paul's gospel did Peter understand at the end of his life?
Les says Peter had a hard time comprehending Paul's gospel at the beginning and never gained full knowledge of it, but by the end of his ministry Peter understood enough to know that the longsuffering of the Lord is salvation.