2 Peter 3:8 But do not overlook this one fact, beloved, that with the Lord one day is as a thousand years, and a thousand years as one day.
At the time the Apostle Peter wrote this letter the scoffers of Christianity were claiming Jesus wasn't coming back. And even today we have those same kind of scoffers. These scoffers naturally are those who openly reject Jesus because they don't want to give up what God says is sin.
Peter addressing the readers of this letter as beloved, is concerned about any effect the scoffers would have on fellow Christians.
A thousand years is as a day and a day is as a thousand years to God, because in heaven, or in eternity time is not an issue with God.
We humans are always trying to compare God to ourselves. The Bible says God is Spirit, so obviously we are flesh, and we age with the years. God is an eternal self existent being, time has no bearing, God created time.
What is left here is like Peter, God Loves mankind. God doesn't take any pleasure in the destruction of the wicked, or sinner's. God's desire is that all would turn from their sin and receive Jesus the Christ and be saved from the destruction of all who reject God's invitation into His Family through Jesus.
So whether it is another day or a thousand years, it is Our Father God's Love to make sure that all who will come to Jesus will come. With God none are left behind.
Well unless they choose to be.
