A Primer on Mortification of Sin

There is also an aspect of the lingering effect of unmortified sin. Owen reminds us that left alone, unmortified sin will do two things: it will weaken the soul and deprive it of its vigor, and it shall darken the soul and deprive it of its comfort and peace. This is what sin does when it reigns in us; it weakens and darkens. Oh, we have great need to mortify sin.