How do we know that repentance and faith are essential for salvation?

In Acts 20:21, Paul emphasizes the declaration of two foundational aspects of the Gospel: repentance toward God and faith toward our Lord Jesus Christ. Repentance involves a turning away from sin and a genuine change of heart, while faith signifies trust and reliance upon Jesus for salvation. Together, they underscore the necessity of acknowledging our sinful state and looking to Christ as the only source of redemption, which is affirmed throughout Scripture as God's ordained means of saving grace.