You ignore democratic consent. Taxation are not decrees imposed by a faceless government. Instead they are imposed by a democratic elected government that are dues we pay in exchange for basic membership in a society and access to services they offer. Saying that of course elected govs can spend our tax dollars unwisely and you have every right to speak out against that.
Also a more basic argument can be made because the strict definitional answer to the question is, no, becuase, taxes are not by definition theft', because taxes are not illegal and the definition of theft includes illegality.
Legislatures are legal and legislatures have the power to levy taxes
And you ignore the fact that taxation is theft of property, as it most definitely is. Just because society decides that taxes may be taken from some, for redistribution based on need, it does not change the fact that it is taking the property of one person, for the benefit of another, and theft is wrong, no matter how you want to justify it.
Turn on your imagination for just a minute to think about something.
Let's say that we have 100 individuals, and five of them are needy, so that society of 100 individuals decides that the 95 of them who are managing to eek out a living, should be required to pay for the other 5 to live comfortably. That's not too much of an issue in that circumstance.
Now, pretend it is 10 years later, and there has been a recession, in which 20 percent of those individuals have lost their jobs. Society still believes that those who are making an adequate living should provide for the 20 percent who have fallen on hard times. That's still acceptable to most of the people in that society.
Now, pretend it is another 10 years down the road, and the recession has continued, and 50 percent of that society is not working, either because they can't find another job, or have found that living off the goodwill of others is pretty damn appealing. Those who are paying the bills are seeing their own disposable income shrinking, through no fault of their own, but the society demands that they keep supporting the society anyway.
This is theft, no matter how you want to slice it and dice it, regardless of what the reasons are, and regardless of who demands it.