My deepest sin fleshes itself in the skin of fear and anxiety (more widely acceptable sins in the Christian arena than that of others). Deeper still lies the bones and muscles of a lack of trust in God's intervention and goodness.
Recently, I've wrestled with bitterness and resentment and yes, even unforgiveness--shameful, dirty and eroding sins to my spirit. I hated that they were there but I felt justified in holding to them; it felt... well... just.
A few days back I was flipping through Josh McDowell's The Secret of Loving, looking for a quote on a totally unrelated topic and I came across a chapter simply titled "Learn to Forgive." That sounds easy. The chapter chews off more than it can adequately flesh out, but it gave me much to ponder. McDowell talks about what forgiveness is and what it isn't and why we struggle to forgive. For me, much of my lack of mercy involves a decrepit understanding of God's grace (and my acceptance of it) over my own life, and then the little zinger. Another reason he posted was "Fear" (insecurity):
"When you forgive someone, you make yourself vulnerable. You might not forgive
another person because you have been burned before and you are afraid of being hurt
again. This is where the health of your own self-image comes in. Until you see yourself as God sees you--no more and no less--you will not be willing to lay yourself open. But, when
you offer to heal the relationship, you have acted rightly in the sight of God,
whether that person accepts of rejects your offer" (143).
The Bible doesn't mince words when it comes to forgiveness. We are do offer it, whether the person is "worthy" of it of not. But we can't do it alone. It does require the Holy Spirit's strength and love through us.