Hardcore anarcho-capitalist libertarians will tell you that all government is theft. They are wrong of course but they kind of make a good point. Government is not necessarily theft but it is necessarily theftish
What does "theftish" mean? A theftish act is one that is very similar to the immoral act of theft. For example, "stealing" food if you are starving is theftish, but because of the universal destination of goods it is not theft. A starving person who takes food without paying for it is not stealing but claiming that which becomes his property by virtue of necessity. Such an act, while not immoral, is very similar to an immoral act and must only be done in truly dire circumstances so as to avoid committing actual theft.
Similarly, government is theftish, because while it is not necessarily immoral, it does run on property taken from someone else. Because it uses money taken from others, certain government actions can easily cross the line between theftishness and theft. Government spending that is completely removed from any benefit to the public is obviously theft. For example, a government sponsored modern art exhibit is not only unsightly, it is immoral, because it is stupid and of no use to anyone. However, even a good and noble government act, such as the commissioning of a postage stamp with my face on it, is theftish and must be considered very carefully before it is done. The government cannot simply spend money on whatever it wants, but must remain strictly within its proper role, lest it commit theft.