From The Divine Dance by Richard Rohr:
Sin is the state of being closed down, shut off, blocked, and thus resisting the eternal flow that we’re meant to be. By a hardened heart or a cold spirit, by holding another person apart in hatred, you’ve thus cut yourself off from the flow.
… Sin is always a refusal of mutuality and a closing down into separateness. In his classic The Great Divorce, C.S. Lewis has the soul in hell shouting, “I don’t want help. I want to be left alone.” Whenever we refuse mutuality toward anything… whenever we won’t allow our deep inner-connectedness to guide us… whenever we’re not attuned to both receiving and giving… you could say that the Holy Spirit is existentially absent from our lives. (Not essentially, however.)
This is indeed the “sin against the Holy Spirit” that “cannot be forgiven,” only because it does not look like one of those naughty things that needs forgiveness! And so we’d never think of even asking for forgiveness, smugly sitting over there in our self-complacent corner. True evil and true sin must be very well disguised to survive. Separation will normally not look like sin, but will often resemble propriety and even appropriate boundary-keeping. “I have a right to be upset!” the righteous soul says. No one ever “deserves” our kindness; in fact, what makes it kindness is that you are not even asking that silly question.