The vilest offender who truly believes
Recognizing the depths of our sin should not lead us to self-loathing and depression, but thanksgiving for what God has done for us.
The hymn "To God be the Glory" has a line that many people gloss over, but is important to our understanding of our faith and God's infinite mercy and sacrificial love:
The vilest offender who truly believes,
That moment from Jesus a pardon receives.
Many people chafe at this: How can someone who has done the most horrible things go to Heaven, while someone who has lived a "good life" but never converted to Christianity go to eternal damnation? Will God really pardon the vilest offender?
Those who cannot see how this is true do not see the depth of their own sin and how much they deserve His wrath. God is perfectly holy, and we are totally corrupted by sin. (See Psalm 14:1-3 and Romans 3:10-12.) We do not see how even many of the "good" things we do are motivated by sin or desire for selfish gain. We have no hope in ourselves, and we deserve God's wrath to fall upon us - and this includes every person in every pew in every church every Sunday.
This is not to lead us to self-loathing and depression, but thanksgiving for what God has done for us and a sincere love for Him. We were enemies of God, and yet He sent His Son to be brutally tortured and to offer His life for us. We have been forgiven an infinite debt, and we love the One who forgave that debt.
But what this also does is help us understand how the worst people can go to Heaven, if they do indeed accept Christ as Savior and Lord - even on their deathbed. If we truly understand the depth of our own sin, we cannot begrudge someone who has done much worse things than we have also being accepted into the Kingdom of God.
This does not mean that we cannot condemn sin or demand earthly justice, and in fact that is commanded by God for our benefit. Recognizing that we are as deserving of Hell Fire as "the vilest offender" is not a call for moral relativism. But we cannot begrudge anyone the infinite mercy, grace and love of God through the sacrifice of His Son. Have you thanked Him for redeeming you of your well-deserved punishment lately?