How do we know the necessity of being born again?

In John 3:3, Jesus explicitly states, 'Except a man be born again, he cannot see the kingdom of God.' This declaration brings urgency to the concept of spiritual rebirth as foundational to entering into eternal life and the fellowship of God. The apostle Paul also supports this in 2 Corinthians 5:17, which tells us that 'if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new.' This new birth not only signifies a transformation in the believer's identity but also necessitates the work of the Holy Spirit in regeneration. It emphasizes that faith is a divine act where God imparts spiritual life to those who were dead in sin, affirming that without this rebirth, one remains separated from God's kingdom.