In "Making Sure You Stay Saved," John Mulligan opens 2 Peter 1:10–11, read within the fuller picture of 2 Peter 1:1–11, to press a question every believer carries: how do we keep walking with Jesus all the way to the end? Peter's answer begins and ends in the same place — with Jesus — and in between it calls us to "make every effort" to confirm our calling and election. We start with Jesus, we change and grow along the way, and we are meant to end up right where we began.
Think of a class of high school students turned loose at Fisherman's Wharf, free to wander and explore, but told to come back to the very spot where they started. The Christian life works the same way. Salvation starts with Jesus, by grace through faith and not by works. We cannot rescue ourselves, we cannot pay for our past, and we cannot earn what only God can give. But grace does not leave us standing still. After baptism we do not camp out at the baptistry; we step into a life of character development, a life of progress, a life under construction.
That construction is the adding Peter describes — goodness, knowledge, self-control, perseverance, godliness, mutual affection, and love. Keep adding these, and "you will never stumble." That promise does not mean you will never commit a sin. It means you will not stumble in the sense of falling away, of turning your back on Jesus and walking off. A believer may sin, confess it, get back up, and keep walking. Peter himself is the proof: he denied the Lord, and yet he got back up, and later it was Peter who preached the first gospel sermon.
So make every effort, and then trust God to take care of the rest. There is no numeric score to reach, no tally of how much goodness or self-control is finally enough. Those who stay the course receive a rich welcome into the eternal kingdom of our Lord and Savior Jesus Christ. Remember both of those names. He is Lord, not merely a suggester or a counselor, and where He leads, we follow. He is also Savior, faithful to forgive when we confess and get back up. There is nothing in this world worth giving up your soul for. Stay the course, come back to the place you started — with Jesus — and the rich welcome will be yours.