How do we know that regeneration is essential for salvation?

Regeneration, or being born again, is critical in the sovereign grace understanding of salvation because it instills the ability to perceive spiritual truth. According to John 3:3, Jesus teaches that unless one is born again, they cannot see the kingdom of God. This new birth is not a work of human will or effort, but a divine act of God through the Holy Spirit, establishing a conscious awareness of one's sinfulness and a need for mercy.

Moreover, Ephesians 2:1-5 explicitly states that we were dead in our trespasses and sins, but God, rich in mercy, made us alive together with Christ. This act of making alive is the work of regeneration, signifying that prior to this divine intervention, no one can respond to God in faith. The transformed heart, which is inclined toward God, is necessary to accept the truth of the gospel, thereby affirming that regeneration is indispensable for salvation.