‘Wherefore, beloved, seeing that you look for these things, give diligence that you may be found in peace, without spot and blameless in his sight, and account that the longsuffering of our Lord is salvation.'
Note again Peter's reference to them as ‘beloved'. His heart was filled with unfeigned love for his brothers, and he yearned for their growth and spiritual advancement.
So in view of their looking for the Day of God, and the new heavens and the new earth, he calls on them to put all diligence into living as he has laid out in 2 Peter 1:4-8; and in 1 Peter 1:13 to 1 Peter 5:11. And his aim is that they may be found ‘in peace', and might be without spot and blameless in His sight. They have their example in the One Who Himself was without blemish and without spot (1 Peter 1:19), following in the steps of the One Who did no sin neither was guile found in His mouth (1 Peter 2:21-22), and indeed was ‘the Righteous One' (1 Peter 3:18). This is in complete contrast to those whose activities resulted in continual spots and blemishes (2 Peter 2:13).
To be ‘found in peace' is a reminder that it is through being accounted as righteous by faith that we have peace with God through our Lord Jesus Christ (Romans 5:1). And it by walking with Him that we continually enjoy that peace, as we put our confidence in His faithfulness, pray with thanksgiving, and bring our requests to God (Philippians 4:6-7).
And at the same time they are to wait patiently ‘accounting that the longsuffering of our Lord is salvation'. The change to ‘Lord' is a reminder of Jesus' part in this salvation, although also including the Father within it. The Lord's longsuffering results in salvation for all His own, when the fullness of the elect are gathered in.