Nevertheless we, according to his promise, look for new heavens and a new earth, wherein dwelleth righteousness, 2nd Peter 3:3.
If there is any one place wherein all major Christian doctrines merge into one vision of the future, it is the kingdom to come wherein Jesus Christ rules the earth while living here on it. Peter called that time the times of refreshing. He also called it or the restitution of all things which God hath spoken by the mouth of all his holy prophets since the world began, Acts 3:19-21.
That time is a time in which, The wolf also shall dwell with the lamb, and the leopard shall lie down with the kid; and the calf and the young lion and the fatling together; and a little child shall lead them, Isaiah 11:6. This is an idyllic time in which the pain of Adam's sin is removed from the earth by the sacrifice of Jesus Christ.
When Adam sinned, part of the curse that came upon the earth was thorns and thistles, Genesis 3:18. Jesus Christ, our Adam from above wore thorns upon his brow. He bore the curse of the earth upon himself and paved the way for a regenerated earth whereon the environment and ways of Eden will prevail upon the entire earth. And the sucking child shall play on the hole of the asp, and the weaned child shall put his hand on the cockatrice' den, Isaiah 11:8.
Man and nature will live in such harmony that there will be four harvests a year in which; Behold, the days come, saith the LORD, that the plowman shall overtake the reaper, and the treader of grapes him that soweth seed; and the mountains shall drop sweet wine, and all the hills shall melt, Amos 9:13. Imagine an impatient plowman waiting for the reaper to finish reaping the last crop so that he can plow again.
Jesus Christ promised his disciples that they would help rule in those days. And Jesus said unto them, Verily I say unto you, That ye which have followed me, in the regeneration when the Son of man shall sit in the throne of his glory, ye also shall sit upon twelve thrones, judging the twelve tribes of Israel, Matthew 19:28. What is important is that he called that time the regeneration. We know of some species that regenerate limbs if they are severed. It is called regeneration because something that was lost is generated again. It is restored to what it was. God will restore this earth to what it was when he gave it to Adam.
The saint of God has a place in that future in which the Spirit of God remakes the earth into that blessed kingdom. And not only they, but ourselves also, which have the firstfruits of the Spirit, even we ourselves groan within ourselves, waiting for the adoption, to wit, the redemption of our body, Romans 8:23. We will one day have bodies meet for that world, but right now we have the firstfruits of the Spirit of God for that world. We each have our new nature on the inward parts; which after God is created in righteousness and true holiness, Ephesians 4:24.
When we receive our new bodies, God will not change anything in our new natures. They are exactly what God wants in that new heaven and earth. They are the firstfruits of the Spirit. To know Jesus Christ and to know the deliverance of Jesus Christ is to partake in the sweetness of regeneration in the inward parts. There will come a day in which God regenerates this entire earth. We have been partially prepared for that day. Romans 8:23 says that we groan waiting to be made complete.
Herein is the key to Titus 3:5; Not by works of righteousness which we have done, but according to his mercy he saved us, by the washing of regeneration, and renewing of the Holy Ghost. Renewing of the Holy Ghost?, when did man ever have the Holy Ghost? Man had the Holy Ghost in the Garden of Eden before he fell. God plans on regenerating this entire world and in that plan is his marvelous plan for the saints of God who live in these last times. He gave us the washing of regeneration on the inward parts. He renewed the Holy Ghost in man in the special relationship he has given us in Christ Jesus. In receiving such, we have received the firstfruits of the Spirit, and like the firstfruits of old, we are offered to our high priest Jesus Christ. To God be the glory.