Setting aside legality, the government cannot rob the people at gunpoint. What happens to a government that doesn't have the support of the people, no matter how many guns it has, can be seen in the recent overthrow of Middle Eastern dictatorships and, earlier, in the fall of the Soviet Union. Guns have to be wielded by soldiers, who are part of the people, and when the people turn against the government it can't count on the soldiers, which means it is likely to lose the guns.
What is happening with taxes is that the people have, through their representatives, decided on a share of the nation's wealth to dedicate to the expenses of public service and how the payment of that share is to be apportioned among the people. It's one thing to disagree with how much spending the government does, or exactly what the money is spent on, or how the tax burden is apportioned. That's all legitimate.
But it's something else again to object to the idea of taxation in itself. Anyone doing that is calling for anarchy. Taxation is not theft and it is not robbery, and to call it that is to object to the very existence of government. Unless you are prepared to be consistent and call yourself an anarchist, you should not go there.