How do we know Jesus is the key to salvation?

Revelation 3:7 explicitly states that Jesus holds the key of David, symbolizing His authority to open and shut the doors of salvation. This imagery reflects His unique role in mediating access to God and His covenant promises. The key represents His control over who enters into covenant relationship with God, emphasizing that He is the ultimate source of salvation. Throughout Scripture, this truth is underscored, showing that no one can gain access to God's presence or partake in His grace apart from Christ's sovereign act of opening individual hearts to the gospel.