How do we know conversion is necessary for salvation?

Jesus unequivocally states in Matthew 18:3 that 'except ye be converted and become as little children, ye shall not enter into the kingdom of heaven.' This highlights the theological significance of conversion, which is understood as a supernatural work of God's grace. Without this inward transformation, marked by a changed heart and spirit, individuals remain unfit for the presence of God. Conversion demonstrates that salvation is not merely a human decision but an act initiated and completed by God. The necessity of conversion is further reinforced throughout Scripture, portraying it as a key component of faith and repentance.