Not sure if your reply is serious or not, so I'll respond as if it is.
Other than the fact that they all have 5 points, the various items aren't the same at all. At least, not as I understand them.
A pentacle (thank you Peale), is a hollow 5 pointed star surrounded by a circle. Like this:

or this:

or this:

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The stars in the American flag are not surrounded by a circle, and are filled in, like this:

or this:

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whereas the Pentagon, the building, looks like... well, a pentagon, like this:

which has nothing star like or pentacle like that I can see.
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So if I'm wrong, it's not because people will see a pentacle and say: "Oh gee, look - part of the American flag. How nice." or.... "Hey, it's the Pentagon! What a proud symbol of Americana." ....
I expect the reaction to be much more along the lines of "What the heck's that?" or "Hey, isn't that that satanic symbol?" (yes, confusing satanism with Wicca. I know the difference). Don't guess we'd ever have the chance to see, but I'd bet money there'd be a big outcry if a Wiccan attempted to hang a pentacle at a courthouse in their home town.
What about satanism now that we're on the topic? One obviously has to draw the line somewhere. Someone claiming to worship a can of beef stew probably has no case on wanting to hang a picture of it on the wall of their courthouse, but satanism (which I know admittedly little about) is a religion numbering hundreds to thousands of followers, apparently (
http://www.cs.uu.nl/wais/html/na-dir/religions/satanism/faqcrt.html).
What if a tax-paying satanist wanted to hang the Baphomet

or this symbol (whose name escapes me):

... What would the reaction be then?
I bet they wouldn't be up there for more than a few hours.
By the way, I'm not sure I've ever seen a Crucifix on a city flag - which flag is that?
As far as the commandments go, I concur with Shmokes -- regardless of whether or not you believe they came from God, only 20% to perhaps 40% of them are actually laws in this country. Given the incredible number of laws in this country, the 2 to 4 commandments that are also laws make up such a small percentage of the overall laws in the country that I'm not sure they are even statistically significant. Perhaps a number of the rest of the laws are off-shoots of the commandments that made it into law (such as stating that copyright laws are an extension of "Thou shalt not steal"), but I don't think (I state think instead of believe because I have not researched a bulk of laws) an overwhelming percentage would trace back to those 2 to 4 commandments that are also laws. For instance, "thou shalt not litter" or "thou shalt not spit on the sidewalk" or "thou shalt not own more than 2 horses" or "thou shalt not stable more than 3 domestic animals within city limits" .... do not appear to have any relation to the 10 commandments at all.
Any other Judeo/Christian/Islamic folks want to weigh in on what their reaction would be to a Wiccan or satanic symbol on their local court house wall? Along with your own personal reaction, what do you think the reaction of your local community would be? Mine would blow a blood vessel I'm sure.
--- saint
multiple edits for spellingYou are wrong.
There are 50 of them on the US Flag, and a building is in the shape of one. Yes I know they are called pentagons, but that is also a pentagram. Just like a cross is shaped like a crucifix, but nonChristians are upset when they see it on city flag.
To me the shapes on the flag represent states; the witches can believe whatever they want to about them.
Our laws are based on the 10 commandments. If you don