v1-4 - The introduction and salutation for Peter's second open letter.
It's addressed to you, in that you've received faith through Christ's righteousness.
Christ has given you everything you need to live a godly life as you grow in knowledge of Him.
v5-12 - You must "make every effort" to continually add to your faith, looking more and more like Christ.
v13-21 - In order to grow in your faith, you must be continually reminded of God's truth.
The gospel is "not a cleverly devised story (v16)," rather it is eyewitness testimony.
In addition to the New Testament, you can rely on the prophetic message (Old Testament) as "something completely reliable... a light shining in a dark place (v20)."
On one hand, we confess we are completely saved by grace without any effort on our own. But as with so many other Biblical doctrines, we must recognize the tension inherent in this truth.
While grace is most certainly a passively given gift of God, the recipients of grace are not to remain passive. Twice in today's chapter you are implored to
Make every effort (v5, 10)
Although both instances read the same in English, two different Greek phrases are translated:
v5 - make every effort to add to your faith...