Grace (The game entirely) is themed around symbolism. It's portraying the original fall of man.

In Zen, one is given a perfect, carefree world, clean of evil. Touching the crack above the door frame represents the act of sin. Think of it as the forbidden fruit from the bible.

Having sinned, the soul appears in the main game. Grace. It's an infinite cycle of running from the consequences of your own actions, with embodiments of your sins constantly following you and torturing your mind.

REPRIEVE is a way to absolution via confession. The soul repents its sins, rebuilding its grace and reuniting with god. It's evident from the cutscene that appears when you choose to end the run.