How do we know the new birth is essential for Christians?

The necessity of the new birth is foundational in Christian theology, as articulated in John 3:3-5, where Jesus tells Nicodemus that one must be born again to see the kingdom of God. At the moment of salvation, God creates a new nature within the believer, providing a desire and capacity to worship Him genuinely. This new nature is in direct opposition to the old sinful nature, which does not seek or please God. Therefore, the new birth is transformative, marking the beginning of a believer's journey towards sanctification and ultimate glorification.