In Luke 12 and Mark 3, Jesus warns us that blaspheming the Holy Spirit cannot be forgiven.
I believe we would be misunderstanding him if we took this to mean, literally, that if we say irreverent things about the Holy Spirit, we incur everlasting punishment. What this is fundamentally about is the rejection of the source of grace.
One way to characterize the Holy Spirit's role in our lives is to say that he is "the Sanctifier." Thus, if we reject the Sanctifier, we reject sanctification. Another way to characterize the Holy Spirit is to say that he is our Advocate. Since we are in no position to advocate for ourselves before God (and who can forget the maxim, "He who acts as his own lawyer has a fool for a client?") it is death to reject our divine Advocate.
All of this gives us a profound understanding of why Pelagianism, the belief that we need no external source of grace in order to make it to heaven, is heretical. On the contrary, we depend on the grace of God to save us from ourselves!
Parallel to rejecting divine help, there is a sin of spiritual and moral despair. In this sin, we regard ourselves as unforgivable, unlovable, unworthy of existence. This, too, is deadly, and amounts to a rejection of God's grace as inevitably fruitless.
Few people plunge irretrievably into the depths of despair during their lifetimes. (Some people who do include gays and lesbians dying of AIDS, abandoned by their "lovers" and turning away redemptive spiritual guidance and women who have had a number of abortions — especially women who became sterile as the result of a botched abortion — and who are tormented by guilt, an unquenchable desire for children and a certainty of unworthiness as a mother and wife.) It is easy, however, to head toward the cliff, and most people do this in their lifetime. There was a time when I did this.
I speak of the temptation to objectify oneself. We need to understand what this is in the context of the truth about God's mercy in order to appreciate why self objectification is sinful.
Self objectification is a matter of rejecting some aspect of our human personhood. The most direct and deadly form of this is to deny our free will. Denying free will sets us on a roller-coaster ride toward the cliff of destruction. Until we can admit to ourselves that we have free will, we will not find hope in reaching out for God's grace. We will not find such hope because we will believe that all moral choices are determined, and, therefore, irrelevant to our eternal fate.
All sorts of people deny the reality of free will and ultimate moral responsibility and nearly all come to the conclusion that this life is all there is. A thoroughgoing moral materialism leads us to a hedonistic and self-absorbed life-style as surely as a flat form of philosophical pragmatism leads us to conclude that the ends justify the means. The conscious and thoroughgoing denial of free will is as deadly a moral trap as walking into quicksand and thrashing about.
People who refuse to ratify a sexual relationship with marital commitment because they're sure that divorce is inevitable, people who treat marriage as "serial monogamy," people with same-sex attraction disorder who enter into the gay/lesbian lifestyle because they "have no other choice," kleptomaniacs, gamblers and substance abusers who deny themselves help because "it's their fate" are all guilty of the sin of self objectification in the specific form of denying free will.
People with these destructive proclivities fail to recognize that God's mercy is offered to them. They fail to recognize that they have a choice to reach out for mercy, forgiveness and divine help with carrying their cross. By denying such help, they choose destruction, even though they don't want destruction.
Human beings make up reasons for their beliefs, even the most destructive of them.
They may tell themselves that "If God were merciful, he would take away this pain or illness." "I may have bad karma at the moment, but I can repair this in the next life, or the one after that... I have all eternity to get it right." "Telling me that I can freely choose faithfulness (or celibacy), and expecting me to do so, is hateful, ignorant and bigoted." "God is merciful. He understands that I'll never change, and he won't hold it against me." All of these are self-objectifying lies. They deny the possibility of, or even the need for, redemptive grace.
The most subtle form of self-objectification is the denial of the reality of natural law. If God has no moral intent in the design of reality (the basis for natural law), then we have no moral responsibility. Morality, itself, then, is regarded as an arbitrary and capricious intellectual construct. It says that the only real law is "positive law." (Parallel to this is the belief that God's design of reality, itself, is arbitrary and capricious.) Without natural law there is no basis for personhood. Without natural law, all of reality is ultimately "nominal." According to this belief, the term "human" has no ultimate meaning.
One form of this nominalist belief is radical existentialism that declares that our humanity is self-determined. That is, we ourselves, as individuals, define what it means to be human. This is the ultimate form of moral relativism, and this, too, is self-objectifying, because it robs moral choice of ultimate meaning outside of ourselves. It's a type of moral solipsism. There are no persons because nothing outside of myself has moral significance. If my morality is a closed, self-referential system, it is nothing. [Cf. 1 Cor 13]
In such a reality, too, grace is meaningless and, therefore, unattainable.