Unless the creator has explictly granted you the right to copy, copying is certainly theft in the legal sense and often in the ethical sense.

Whether or not you agree with the legality of it is irrelevant, the fact is that it's illegal for you to make copies of software that you are not authorized to copy.

Ethically, it's not fair to the people who build these apps to be deprived of the revenue they would earn from your usage of it.

They don't have a right to your money, but then, you don't have a right to their software either.

Your second, third, and fourth sentences do not support your first. Copying software without paying for it (when the author has not licensed you to do so) is arguably immoral, often unethical, and nearly always illegal...

...but the claim of the gp was that it is not "theft" as such. Copying something from someone and taking something away from someone are not the same.

Drawing a definitional distinction there helps us to have a meaningful debate about the moral, ethical, and legal dimensions; the only benefit to muddying the distinction is as a rhetorical tactic to confuse the issues.

The law recognizes unauthorized copying as stealing of intellectual property. This is not difficult to understand.

Don't be so simplistic, that's like saying that stealing a car isn't theft because it is just driving and anyway you are just moving it somewhere else. The economic consequences of copying are a deprival of revenue, that is tantamount to theft and 'theft' is a good word to describe it.

What really ticks me off about thieves is how they try to quibble over definitions as though that changed the consequences. Making an unauthorised copy of something that is supplied for money IS theft.

That is sheer propagandist nonsense. You do recognise the basic unassailable physical difference between copying something and removing it, don't you? The differences of economics follow from the differences in physical fact.

Consider this quote from Landes and Posner -- one of the primary orthodox authorities on the matter:

"Copyright protection -- the right of the copyright's owner to prevent others from making copies -- trades off the costs of limiting access to a work against the benefits of providing incentives to create the work in the first place. Striking the correct balance between access and incentives is the central problem in copyright law."

Is that how physical goods, and theft, are understood? No. To say there is a tradeoff is to say both are good: that is, copying is good.

Read it: http://cyber.law.harvard.edu/IPCoop/89land1.html -- and learn something.