Well, Tom and Zev said most of what I’d have to say in response to the OP –
But I think I need to add that what I as a sincere Christian find more offensive than either is a person who, claiming to espouse Christianity, sits in judgment over other people. (This does not preclude actively disagreeing with their views, but rather deciding for God whether they’re eligible for His salvation and whether they oughta “find Him” right now, etc.)
I’d have to say neither is particularly offensive. As a loosely-practicing-Methodist, I’m content to respect ALL religions, regardless of their nature. (Even when you believe in no deities, as atheists do.)
That said, I find it immensely distasteful 
when other believers try to force their religious beliefs on me - whether they be atheist, Catholic, Jew, Muslim, Baptist, Buddhist, etc.
So long as you’re not ramming your holy scriptures down my throat, I really don’t care what you are. 
My take on this has always been that you have to sink pretty low to worship a being that was fired from his last job.
BTW The Satanic "Churches mentioned have about as much to do with Satanism as the Girl Scouts have to do with idetifying enemy targets. It’s just a name they picked out of a hat.
Regarding what Polycarp posted, I would point out that Jesus was always in conflict with those that thought they were more religious and tried to inflict their ideas of him and those around him. Many times those around him were guilty of sins, but were not sticking their noses in other peoples business. IMHO, true followers of Satan (if they really exist) would be more objectionable, because they would be breaking a commandment.
Based on the Christianity I grew up with and still see around me where I live, I would have to go with athene1765 on this one.
The argument I hear the most is how life has no meaning in my view. Usually spoken with wide-eyed sadness. The other is how I am going to burn in hell like a dog if I “don’t decide.” Gotta love family
Satanists are viewed, by these people, with a fair measure of fear and contempt, but at least satanists (or devil-worshippers) believe in the same hierarchy that they do and are, for that reason alone, easier to understand.
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I will also add that I wish I had experienced people like Zev, Polycarp, and tomndebb prior to my atheitization (it’s my word, but feel free to use it royalty free)
It would have been nice to hear a rational, truly Christian take on things. I may have left the faith walking, rather than running with my ears plugged!
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Thanks for the compliment FordPrefect, but you do realize I wouldn’t have given you the “rational, truly Christian take” on anything…
Zev Steinhardt
Not quite. While they don’t actually worship Satan as described in Christian mythology, they do have good reasons for picking the name. I’ll explain more later, but I’m at work now, and I don’t really want to visit those sites here.
OP: It depends on how you ask the question and in what context.
If you ask them abstractly, Christian to Christian, over coffee, many might say Satanists concern them more as both a physical and a spiritual threat, and they might almost totally dismiss atheists as such a threat. (No cite, just personal experience from my Christian days.) However, it has also been my experience that Christians are more personally threatened by atheists than Satanists in a very special sense. (Again, personal experience from my conversations with Christians during my atheistic days–I know, I need to make up my mind, don’t I.)
I perceive that Christians generally show strength in the face of evil, but somehow show nervousness in the face of atheism. I think it’s a fear of the unknown being greater than fear of the known.
Satan-worshippers carry a supernatural crutch to help them through their daily lives, much like the Christians. Therefore, true followers of Satan (all eighteen of them) are at least understood, if not agreed with.
Atheists (all teeming millions of them), on the other hand, somehow make it through life without supernatural assistance (that they know of). This is totally foreign and incomprehensible to your average religious Christian.
Many times I’ve heard Christians say, “Well, at least he believes in something.” This statement always blows me away. I mean, why would it be good from a Christian jpoint-of-view if another person holds incorrect spiritual beliefs than none at all? Perhaps, as crutch-walkers themselves, it is because it makes them more nervous to see someone walking (at least appear to be walking) without a crutch than it does to see someone walking with the wrong color crutch.
Well put. Some of my Christian relatives seem more worried that I don’t believe there are demons and spirits flitting about in this very room, than someone who not only believes in them, but would worship them. It seems to somehow validate their belief. I always ask “Is there a devil in this room right now?” Apparently there always is! That might be another good discussion point.
OK. I guess I was never a “real Christian” by typical fundie standards, but when I was younger, I would have said this:
Satanists, being aligned with evil, are on the wrong side. Atheists are neutrals, or more to the point, subscribe to a different worldview. So Satanists are the enemy by their own definition–and atheists are dangerous because they could lead people away from the true worldview. But it would piss me off that Christians would accuse the atheist of “serving Satan” when he was just kind of unaligned.
The thing is, Satanism isn’t a plausible worldview. It’s just perversity, given a name to fit into a Christian worldview. Calling yourself a devil worshiper is stupid. Atheism, on the other hand, is a plausible worldview. In fact, it’s the most plausible. So Christians want to reclassify atheists as “servants of Satan” to make them seem dreadful, & keep the young in the absurd Christian worldview.
You just made my afternoon a little more tolerable. 
I am well aware of their justifications. They may have reasons for picking the name. I will leave it up to each individual whether they are “good” reasons.
Their movement would more realistically be called The Hedonist Church of America.
They chose Satan as their symbol solely for the shock value.
And BTW they admit this…
Great! More dissillusionment!