Why do Christians say we must be born again?

The necessity of being born again stems from Jesus’ own teachings, most notably in John 3:3, where He states that one cannot see the kingdom of God without new birth. This new birth, or regeneration, is a work of the Holy Spirit, granting an individual spiritual life and the ability to have faith in Christ. Without this transformation, a person remains spiritually dead and unable to respond to God. The new birth is God’s initiative, allowing a sinner to embrace the gospel and experience true salvation.