In my opinion, part of the reason the old Puritan gospel preachers were so good at displaying the grace of Jesus was because they understood sin so well. We tend to simply scratch the surface by saying sin is lying to our wives, looking at porn, disobeying our parents, and so forth. To be sure, those are sins, but (as the saying goes), ‘you ain’t seen nothin’ yet.’ Robert Murray M’Cheyne explains the depths of the sinful heart in a sermon on Jeremiah 17.9-10 (chapter 5 of his “Sermons“). I recommend reading these quotes out loud – as Luther said, preach to yourself.
“…The most awakened sinner does not see the ten thousandth part of the wickedness of his own heart. You are like a person looking down into a dark pit – you can only see a few yards down the sides of the pit; so you can only see a little way into your heart. It is a pit of corruption which is bottomless: Who can know it?“
“…You are like a traveller looking down into the crater of a volcano; but the smoke will not suffer (allow) you to look far. You see only a few yards into the smoking volcano of your heart…. There are chambers in your heart that you have never yet seen into – there are caves in that ocean you have never fathomed – there are fountains of bitterness you have never tasted. When you have felt the wickedness of your heart to the uttermost, then lie down under this awful truth, that you have only seen a few yards into a pit that is bottomless – that you carry about with you a slumbering volcano – a heart whose wickedness you do not and cannot know.”
God in his grace doesn’t show us all that sin at once, or we’d be undone and melt like wax. Honestly, if we could see way down into the depths of our sinful heart, we would probably suffer biologically (stroke, mental breakdown, dark depression, suicide, etc.). Thankfully M’Cheyne ended the sermon with the heights of grace.
“[Christ] was the only one that knew the wickedness of the beings for whom he died. He that searches the hearts of sinners died for them. He knew what was in men; yet he did not abhor (hate) them on that account – he died for them. It was not for any goodness in man that he died for man. He saw none. It was not that he saw little sin in the heart of man. He is the only being in the universe that saw all the sin that is in the unfathomable heart of man. He saw to the bottom of the volcano – and yet he came and died for man. Herein is love!”
“When publicans and sinners came to him on earth, he knew what was in their hearts. His eye had rested on their bosoms all their life – he had seen all the lusts and poisons that ever rankled there; yet in no wise did he cast them out. So with you. His eye hath seen all your sins – the vilest, darkest, blackest hours you have lived, his pure eye was resting upon you; yet he died for such, and invites you to come to him; and will in no wise cast you out.”
My sin! O the bliss of this glorious thought!
My sin – not in part but the whole
Is nailed to the cross and I bear it no more
Praise the Lord! Praise the Lord O my soul!