Why is having a mediator necessary for salvation?

The necessity of a mediator arises from the stark reality of human sinfulness. Romans 3:23 states, 'For all have sinned and fall short of the glory of God,' indicating that no one can stand before a holy God on their own merit. The law is unable to save and only serves to reveal our fallen state. Jesus, being both fully God and fully man, is the only one who can mediate effectively, having fulfilled the requirements of the law and satisfied divine justice through His sacrifice (Hebrews 10:14). Without Him, we have no hope of reconciliation with God; hence, His mediatorial work is essential to our salvation.