What you're saying is pretty much correct because few Christians have a sense of humor or can distinguish sarcasm on the internet. We do joke about eating babies, and while I hope that most people would be able to see that as pure satire, there are many who would take it seriously partially because they want to believe it's true.
But frankly, I really don't think that joking about worshiping Satan or not is going to help our standing in the fundamentalist or even mainstream Christian view, since most of them want to willingly lie about us worshiping Satan anyway. To the fundies, anything not worshiping their god is worshiping the devil. There is no middle ground with these people. They're so set in the "if you're not for us you're against us" mentality that even if all atheists volunteered in soup kitchens, donated half their money to the poor, and cured the problem of world hunger, they'd still claim that we were serving Satan.
But frankly, I really don't think that joking about worshiping Satan or not is going to help our standing in the fundamentalist or even mainstream Christian view, since most of them want to willingly lie about us worshiping Satan anyway. To the fundies, anything not worshiping their god is worshiping the devil. There is no middle ground with these people. They're so set in the "if you're not for us you're against us" mentality that even if all atheists volunteered in soup kitchens, donated half their money to the poor, and cured the problem of world hunger, they'd still claim that we were serving Satan.
Christian apologetics is the art of rolling a dog turd in sugar and selling it as a donut.