You're not asking this in good faith.
However, nobody has actually tried to simplify an answer yet.
Taxes are a form of social contract between all taxpaying members of a country.
While it is not truly voluntary, it it also only applied when a person takes part in specific aspects of the social structure. So it can be avoided, just not without eschewing the benefits that come with being part of that country.
By partaking in the aspects of life in a country that incur taxes, you are, indirectly, agreeing to pay them that may or may not be fair. It may or may not give you any feasible alternatives to life in that country, and it decidedly does not leave any pleasant options. But you can avoid taxes, without legal consequences for not paying them, by not engaging in taxable activities.
It would suck for sure.
Now, does that mean taxes aren't theft? Define theft.
If I come to up to you and say "hey jimbob, if you come over here and mow my grass, I'll give you a gallon of milk. But, you gotta give a half pint of that to Gary over there because he gets a cut of all the milk that I give to people since he makes sure the cows stay healthy", is Gary stealing?
Gary is also providing a service. Me and Gary have a mutually beneficial agreement. You do not have to mow my grass. But once the offer is extended, and accepted, trying to say that Gary stole anything from you is not going to be a believable statement.
That's what taxation is. It's an agreement between everyone involved that "Gary", the government, gets a cut of money out of various exchanges of funds. In return, ideally, Gary keeps providing services to everyone.
Again, that's in an ideal world. In reality, not every government actually provides services to the taxed. Often enough, governments make every effort possible to not provide services as expected. But that's not the same thing as taxation itself being theft, it's a given government stealing while using taxes as the method.
So, what choices do you have to avoid taxes?
Well, you'll have to live life without monetary income, since you likely live in a country that taxes that. Difficult, but not impossible. You'll have to avoid owning taxable property. Here in the US, that's usually vehicles, homes/land, and similar real property. That's not actually difficult if you live in the right places, but if you're also not making monetary income, your choices for where to live become very unpleasant if you don't have very good friends and family to rely on.
You'll also likely have to avoid buying most things, since sales taxes exist. That's the really hard one to avoid because most people take part in the social agreement and will not give you goods or services without monetary exchange. Not impossible, but it's going to be a brutal life.
So, the choices absolutely are not fair. Since you also can't go anywhere livable without dealing with taxable transactions, you can't just opt out entirely and go live in the woods away from governments. Everywhere livable is owned by a government somewhere.
But that still doesn't make taxation itself theft, only specific implementations of taxation, and that is a different thing.