Peter now returns to a theme from chapter 1, where he said he wanted to remind his readers of the truths of the gospel...so that after my departure you may be able at any time to recall these things.
Peter begins by denying any use of a common source for religious works...creative human thought...he says with full authority, we did not make up this story...
Peter begins the transition from our justification in Christ to our sanctification in verse 5 with the words “for this very reason” – what reason? The gift of faith in Christ
This reveals to us that Peter was under the authority of Jesus Christ, that he submitted to the lordship of Jesus, and that he held no inherent authority of his own.