I did not see taxation as theft because is through taxation that state can build roads, health care facilities, schools, fight external aggression against the state, pay state workers salary and finance research for technological development. But some tax collectors are theft and they also stole from state.
If taxes are 50% of your income or more then I believe that is theft. It seems to me that the government spends so much money inefficiently. What is that but theft?
In certain countries such as Germany and Sweden, the tax rate is above 50% if you take in to account the indirect taxes. Personally, I believe that a reasonable rate of income tax may be around 10% to 15%. On top of that, the government should have a VAT at 5% to 15%, depending on the type of commodity. Capital gains tax must be scrapped, as it is similar to double taxation.