It takes one to know one. I can identify another regenerate person because I know what God’s Holy Spirit has done to me. I know how He has changed me, so I can recognize similar changes in other people. But if a person has not been regenerated by the Holy Spirit, he will not know or recognize or value regeneration in others. Because the marks of regeneration are personal and subjective, and because regenerate people are intimately aware of how God has changed them, because they know that the changes in their own lives are real, they can trust that similar marks in other people are equally real. The reality of the Holy Spirit in their own lives provides a guarantee of the reality of the Holy Spirit in the lives of others who are similarly marked. The guarantee of God’s reality and of the power and presence of the Holy Spirit is found in the heart of the believer. My own changed life is the proof and guarantee of God’s reality. Your own changed life is the proof and guarantee of God’s reality.
We are the proof of the existence of God. It is not found in an argument. It is not found in the Bible. It is not found in history. It is found in my own regeneration, and your own regeneration. And if a person is not regenerated, it is not found apart from God’s judgment.
The whole world stands under the judgment of God as a result of Adam’s sin and is exacerbated by our own sin. When God’s judgment is manifest, all doubt about God’s reality is quelled because God’s judgment has a drastic effect upon this world and the world to come, in eternity. By God’s grace alone God moves to rescue people from this context of damnation in this fallen world. God’s plan will take many generations to unfold in its full glory, and when it is complete all evil will be destroyed and all extant people will live in the context of God’s salvation. The process of salvation will be progressive in that evil will be eliminated over time as increasing numbers of people find themselves regenerated by the grace of God. —from a recent sermon on 2 Corinthians 1:21-24