I read the initial greetings to epistles all the time, but I never noticed something almost all of them share: a healthy and comprehensive view of Jesus's righteousness. Look at 2 Peter's first verse: 1Simeon[a] Peter, a servant[b] and apostle of Jesus Christ,
To those who have obtained a faith of equal standing with ours by the righteousness of our God and Savior Jesus Christ:
Peter understood (1) that the righteousness of Jesus is essential to salvation and (2) that without it, we would not be saved. "by the righteousness of Jesus Christ" we have reached a standing of righteousness. A metaphor for this would be washing your clothes. If you wash your clothes in dirty water, they will not be cleaned; if they are washed in clean water, they become clean. One of the bloggers I read, Mark Lauterbach, is currently in a series on applying Jesus's righteousness: something we don't often do.