II Peter 1  Peter addresses those  "who have received a faith of the same kind.. " the kind of faith that comes by "the righteousness of our God and Savior, Jesus Christ"..  and encourages them and us to be "diligent to make certain about His calling and choosing you.. "

It is in the "knowledge of God and of Jesus our Lord" that we find grace and peace.  It is the way we can see "His divine power" that has "granted to us everything pertaining to life and godliness, through the true knowledge of Him who called us by His own glory and excellence." 

Jesus has "granted to us His precious and magnificent promises..."  so that we can be "partakers of the divine nature".  This is our foundation and living hope..

But.. we must be "diligent"  - we need to pay personal attention and care to not only KNOW these truths but to increase in these qualities..

By faith, our character must begin to be shaped by Christ..
Moral excellence or virtue will continually grow, being refined and made purer by the sanctifying work of the Holy Spirit.
Knowledge - of the Lord Jesus and of His Word as well as a personal knowledge of Him as Savior, Master, King, Friend, Redeemer, Sanctifier, and Healer continues to grow.
Self-control - is evidenced in our lifestyles, our homes, and our actions.
Perseverance is increased, so that we remain steadfast in Christ no matter the circumstances.
Godliness, brotherly kindness, and love are genuine qualities witnessed by unbelievers and believers alike.. to the glory of God.

Then.. we will be "neither useless nor unfruitful".
Peter tells us to "practice these things".. so we will not stumble, but will enter "into the eternal kingdom of our Lord and Savior Jesus Christ". 

Father in heaven, establish us in these truths, in Christ Jesus our Lord. amen.