Why could Peter write 1 Peter 2 with confidence about Paul's doctrine?
Peter could write 1 Peter 2 with confidence because Paul's epistles and doctrine had already been circulating for a long time. These epistles were written shortly before Peter and Paul were both martyred, so Paul's revelations were well established, allowing Peter to reach that conclusion.
Les teaches that although some might think he makes too much of Paul and leaves Peter in the shadows, the point is to go back and see what Peter himself said. After the revelations given to Paul had been around for a long, long time, Peter could write 1 Peter 2. These little epistles were written just shortly before Peter and Paul were both martyred, meaning Paul's epistles and Paul's doctrine had already been out there a long time. Therefore Peter could come to this kind of conclusion. In the chapter, Peter uses the analogy of newborn babes hungering for the milk of the Word so they may grow, and he speaks of Christ as the living stone disallowed by men but chosen of God and precious. Peter writes to believing Jews of the dispersion, but that does not mean it does not apply to us, and he says believers also, as living stones, are built up a spiritual house, a holy priesthood, to offer up spiritual sacrifices to God by Jesus Christ.