The cross plus the resurrection ensures it is a done Deal.
The cross and death of Christ is evidence of God's wrath poured out against sin. Not that Jesus was sin...He took upon Himself our sin so we would could be free from paying for our sin. Sin...ALL SIN...is is paid for in full, through the complete work Jesus finished on the cross and validated by His resurrection.
Now the LIVING JESUS, is proof positive of God's forgiveness, mercy, grace and love.
Jesus died and was raised to life again to give us the Gospel of Grace, grace that is greater than all our sin!