Earlier quoted context omitted.
This comment is simply incorrect. The gas limits do make smart contracts decidable. It is a mathematical fact. Bringing the idea that things have gone wrong with Ethereum as proof to the contrary is completely absurd. Things have also gone wrong with Bitcoin [1]. Is it undecidable now too? [1] https://en.wikipedia.org/wiki/Mt._Gox
Indeed. All you have to do is test every possible input, in much the same way that any computation on a real computer is technically decidable because the limited amount of RAM means that it can only have a finite number of states. Neither of those limits actually makes solving the problem feasible in practice.
That's the point. Theoretical limitations has no bearing on solving the practical problem. That is why RichardHeart's original point [1] is wrong.
[1] The halting problem states you can't predict what a turing complete program will do, until you run it. This means to some degree, that you can't predict what your "smart" contract will do, until it does it. Thus turing completeness causes security to be far, far harder than non turing completeness. This is how you lose the millions of dollars as the DAO did after it passed audits.