23 for you have been born again not of seed which is perishable but imperishable, that is, through the living and enduring word of God.
Here Peter is telling them that their sincere love for others is certainly possible, since they now have a new life. This new life comes from an imperishable seed; that which is planted in them by the Holy Spirit and through the living Word of God (which is actually Christ, see John 1:1).
There is no better thing we can do on Thanksgiving Day than to look up to heaven and begin thanking God for His great love to us—for giving us His only Son, that he would die on the cross in order that we may have eternal life.
John 3:16
For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.
This is our great prize from heaven. There is no better gift. Our joy and thanksgiving overflows on this day. All other things we are thankful for pale in comparison to that great gift. Nonetheless, with hearts full already, with eternity awaiting, we thank God for all other good things. His basket of gifts fills our life. Our joy overflows.
22 Since you have in obedience to the truth purified your souls for a sincere love of the brethren, fervently love one another from the heart,
Here we have an obvious break in the narrative, where Peter turns more toward application. In verses 13-17 he encourages the reader toward obedience and holiness. Now he sharpens the scope toward love of the brethren. As Peter put it, in their obedience to the truth (as obedient Christians) they acted to purify their souls so that they were able to fervently love one another from the heart.
21 who through Him are believers in God, who raised Him from the dead and gave Him glory, so that your faith and hope are in God.
It is through Christ and His sacrifice for us that we are believers in God—who raised Christ from the dead and gave Him glory when He brought Him back to heaven. Hence our faith and hope are to be in God.
20 For He was foreknown before the foundation of the world, but has appeared in these last times for the sake of you
He was chosen by God before the world began for the purpose of giving His life for us; and He appeared in these last days at just the right time to carry it out.
18 knowing that you were not redeemed with perishable things like silver or gold from your futile way of life inherited from your forefathers, 19 but with precious blood, as of a lamb unblemished and spotless, the blood of Christ.
In our evaluation of things, seeing what value Christ put on us, that He gave His very life-blood for us (His precious blood; unblemished), this may influence your conduct.
17 If you address as Father the One who impartially judges according to each one’s work, conduct yourselves in fear during the time of your stay on earth;
If we know that God is our Father and that He will judge us fairly according to our works, we ought to know that He will indeed see everything we have done, whether our works are valuable and enduring, or invaluable and shallow (1 Cor. 3:12-13); thus, we ought to not take lightly what we do—how we conduct ourselves.
15 but like the Holy One who called you, be holy yourselves also in all your behavior; 16 because it is written, “YOU SHALL BE HOLY, FOR I AM HOLY.”
As God’s children we are to be holy as He is holy. Here Peter quotes from Leviticus 11:44; but I think we should also consider God’s original plan for man. In His creation He created man and woman in His own image (Gen. 1:27). Hence, we were created with the desire and capacity to be holy, because that is one of the characteristics of God.
14 As obedient children, do not be conformed to the former lusts which were yours in your ignorance,
As Christians we must be obedient to God. That is our calling and it should be our desire—to please Him in everything. Before we were believers we followed our own desires (our lusts). That is all we knew. We had no other direction in life. The world, and our flesh, is all we knew. God and Jesus were alien to us.
13 Therefore, prepare your minds for action, keep sober in spirit, fix your hope completely on the grace to be brought to you at the revelation of Jesus Christ.
A better translation of the first line may be, “Gird up the loins of your mind,” which meant in those days to gather up one’s robes in order to run without hinderances, here applying to one’s thoughts, to keep our thoughts uncluttered or unhindered by the world. To “keep sober in spirit” means to be self-controlled and clear-minded, not given over to worldly and impure thoughts.
As for our hope, I think a better translation here is, “hope to the end, or “to keep your hope on.” The word “completely” I think is confusing. Hence, we are to fix our hope on the grace that will be brought to us when we see Jesus. The idea here is that we are to look more to the future, looking for His coming. Instead of always getting bogged down with all our earthly things, we ought to be keeping our mind on heavenly things.