I'll tell you up-front that I do believe in a God and that this God is the uncaused cause that set everything else into motion. As this is a personal belief, it won't have much to do with my response to you, but I thought I'd mention it to add some perspective. By "personal belief", I mean "go form your own". I for one cannot stand the mindless group-think experience of most churches I've visited and the "security" of being surrounded by the like-minded is worthless. I think Big Questions like "is there a God?" are things you have to decide for yourself.
OK. I find the belief in unfounded god/s is one of the leading causes of murder, rape and mutilation etc throughout history. It has also repeatedly held humanity's progress back and tend to be non-democratic and unreasonable in nature having no place in schools or modern life in general.
The massive mainstream religions have become like a corrupt government. They served a purpose and provided people something they felt they needed, but various control freaks long ago realized they can also be used to control people. Like Jim Marrs says, religion and the monetary system are the two major methods of controlling people. This doesn't mean that currency of some kind has no legitimate use (barter has lots of problems) and it likewise doesn't mean that religion can only control people.
I mean, I've read the Bible. I'm not an expert, but I can say that I'm well familiar with it, specifically the words of Jesus Christ. When I read the words attributed to him, I see exhortations to be humble, to love your neighbor as you love yourself, the importance of forgiveness, turn the other cheek, etc. I've read multiple translations and they all agree on this point. I just can't find any teaching of Jesus that can be construed as "murder, rape, torture, etc are all perfectly acceptable". Those calling themselves Christian and claiming to have read the same Bible should have observed the same.
I argue that if there was a god he/she/it would not need any believers nor would he need them to be offended to defend his/her/its name or honour.
The actual concern for this comes from the idea that the Creator wants to have a relationship with the created, rather than just watch us like an aquarium or snow globe. It's also believed that people have an inherent longing for such a connection and don't have a full life without it.
The perversion used to control people is this idea that you must behave a certain way and become a certain typecast sort of person or else you're faulty in some serious way. It's just a way to enforce conformity, not in a "top-down" way but in such a way that the conformists themselves would feel ashamed to appear otherwise.
I've also argued to more than one religious person, that I doubt a term like "god dammit" would actually offend any serious God-concept. It seems like a childish position to me, to envision God as some sort of scolding parent. I know human beings who wouldn't actually be offended by terms they dislike; why should Almighty God be more petty than they? It just makes no sense to me.
If I believe, wholly and deeply in divine pink unicorns a legislation demanding that others respect such an unfounded belief would be an insult.
If you also had multiple witnesses providing written accounts of this, and said unicorns performed what appeared to be miracles in front of large crowds, and many people found this convincing and credible, well then you might be onto something.
The very questioning of belief is repeatedly a cause to offend some. After all, the only unforgivable sin is to deny the holy spirit, should such a spirit exist in the unlikely event that spirits become factual.
My own concept of God includes a desire for us to question everything worthwhile, and this certainly qualifies. Einstein said "the most incomprehensible thing about the universe is that it is comprehensible". I personally wouldn't want to create mindless robots with no sense of awe or mystery, no genuinely satisfying curiosity; they would never reach their full potential. If I can see what would be direly wrong with that, I assume a being infinitely more advanced than myself can also see this.
If by "unforgivable sin" you refer to Mark 3:22-30 and Matthew 12:31-32, this refers to permanently rejecting the Holy Spirit. In the context of Mark 3:22-30 the Pharisees tried to falsely attribute Jesus's powers to Satan ("ruler of the demons"). This represents a conscious rejection, a misunderstanding so profound that its bearer actively resists truth, even when it happens in front of them. It's the idea of someone seeing an act of God and calling it evil. In many matters not involving religion, this is how psychotic people operate: they've convinced themselves that the wrong thing to do is expedient, justified, expected, etc and therefore good ("greater good" is a common one).
Like Bill Hicks mentioned, I personally suspect that we are God's way of experiencing Itself subjectively. That would make questioning, reasoning, and personal refinement all the more important.
Not exactly a front-page story anymore, but when I read your post, it got me thinking.