Suppose that one man takes your car at gunpoint. You would say that that man is a thief who is violating your property rights. Now, let's suppose that it's a group of five men forcibly taking your car from you. Still wrong? Still stealing? Yep.
Okay, now it's ten men that hold you at gunpoint. But, before anything else, they take a vote. You, understandably, vote to keep your car. But the ten of them vote in favor of taking it. So you are outvoted - ten to one. They take the car. Still stealing?
What if we add specialization of labor into the equation? One man acts as the negotiator for the group, one takes the vote, one oversees the vote, two hold the guns, one drives, and so on. Does this make it acceptable?
Now the group is two hundred strong, but - after forcibly taking your car - they give you a bicycle. That's right: they do something nice for you. Is this still stealing? In fact, not only do they give you a bicycle, but they also buy a bicycle for a poor person. Is this even wrong?
What if the group has a thousand people? Ten thousand? A million? How big does this group have to be before it becomes acceptable for them to forcibly take your property away without your consent? When, exactly, does the immorality of theft become the alleged morality of taxation?