How do we know justification and regeneration are true?

Justification, which is the act of God declaring a sinner righteous through faith in Jesus Christ, is rooted in Scripture as seen in Romans 5:1, which states, 'Therefore, having been justified by faith, we have peace with God through our Lord Jesus Christ.' Regeneration, the process by which one is made spiritually alive, is also confirmed in the Bible, specifically in John 3:3 where Jesus states, 'Unless one is born again, he cannot see the kingdom of God.' Both acts are part of the double cure that ensures our standing before God and our transformation into His likeness.