21 who through him are believers in God, who raised him from the dead, and gave him glory; so that your faith and hope might be in God. 22 Seeing you have purified your souls in your obedience to the truth through the Spirit in sincere brotherly affection, love one another from the heart fervently: 23 having been born again, not of corruptible seed, but of incorruptible, through the word of God, which lives and remains forever.

24 For,

“All flesh is like grass,
and all of man’s glory like the flower in the grass.
The grass withers, and its flower falls; 25 but the Lord’s word endures forever.” [1]

This is the word of Good News which was preached to you.

Matthew Henry's Commentary on 1 Peter 1:21-25

Commentary on 1 Peter 1:17-25

(Read 1 Peter 1:17-25)

Holy confidence in God as a Father, and awful fear of him as a Judge, agree together; and to regard God always as a Judge, makes him dear to us as a Father. If believers do evil, God will visit them with corrections. Then, let Christians not doubt God's faithfulness to his promises, nor give way to enslaving dread of his wrath, but let them reverence his holiness. The fearless professor is defenceless, and Satan takes him captive at his will; the desponding professor has no heart to avail himself of his advantages, and is easily brought to surrender. The price paid for man's redemption was the precious blood of Christ. Not only openly wicked, but unprofitable conversation is highly dangerous, though it may plead custom. It is folly to resolve, I will live and die in such a way, because my forefathers did so. God had purposes of special favour toward his people, long before he made manifest such grace unto them. But the clearness of light, the supports of faith, the power of ordinances, are all much greater since Christ came upon earth, than they were before. The comfort is, that being by faith made one with Christ, his present glory is an assurance that where he is we shall be also, John 14:3. The soul must be purified, before it can give up its own desires and indulgences. And the word of God planted in the heart by the Holy Ghost, is a means of spiritual life, stirring up to our duty, working a total change in the dispositions and affections of the soul, till it brings to eternal life. In contrast with the excellence of the renewed spiritual man, as born again, observe the vanity of the natural man. In his life, and in his fall, he is like grass, the flower of grass, which soon withers and dies away. We should hear, and thus receive and love, the holy, living word, and rather hazard all than lose it; and we must banish all other things from the place due to it. We should lodge it in our hearts as our only treasures here, and the certain pledge of the treasure of glory laid up for believers in heaven.