The inheritance that the Apostle Peter is writing about is really the inheritance of the Lord Jesus, and He has chosen to share His inheritance with us who believe. This inheritance is mentioned in Revelation 21-22, where the Apostle John describes the new heaven and the new earth as a place where believers in the Lord Jesus Christ will inhabit the kingdom of God.
In the New Earth all living things will find their sustenance in the presence of our God, the Lord Jesus Christ. In heaven, every longing that we have ever known will be realized. Christ's promised inheritance is guaranteed to the believer in Christ and it is secured in heaven by God's power through the resurrection of Christ! In eternity, we will fully experience ultimate fulfillment that we were created to know partly due to the fact that there will be nothing to hinder us of the pursuits of our hearts.
Peter describes this inheritance as never perishing, never spoiling, and never fading, because it is kept by God's power in heaven for us. The word "kept" means "to guard." The believer's inheritance in Christ is guarded in heaven. Here the Apostle Peter used a perfect passive participle meaning the already existing inheritance is presently under guard in heaven. And, heaven is the safest place there is because it does not suffer from the presence of sin and death.
It is so easy for us, especially while we are suffering persecution, to lose sight of this eternal perspective that Peter is describing here. We most often lack an appreciation for the future because we so quickly forget the terrors of hell from which God has saved us through the sacrifice of His Son on the cross. The earth as we know it will end in flames, and God will make a new heaven and a new earth.
As believer's we sometimes develop a myopic view of what time is in the context of the eternal. Time, with reference to eternity, is just a speck of sand. This temporal earth is, in comparison to the eternal, nothing. To be defined by the nothing as opposed to the eternal is like settling for a five hundred thousand dollar home here on earth rather than a multi-gazillion dollar home in eternity. There simply is no comparison. And this inheritance is locked up in the bank vault of heaven, guarded against every intruder who might desire to take it from us.
Finally, think of those whom you admire the most. Think of the qualities that each of these people possess. Think of why you enjoy their presence. The Lord Jesus Christ is all of those qualities and more. You see, He is our inheritance, and He is the One who will complete us. It is hard for us to wrap our minds around this concept right now, but He is everything we have ever desired and more. In heaven, we will know, in a perfect and an eternal way, an authentic and lasting union with Him. That's a prize to keep our eyes on while here on this fallen earth. This all means that heaven, although the coolest place ever, is far more than just a destination. Heaven truly is a person and His name in the Lord Jesus Christ.