You are still wrong. There IS a definitive answer, and we DO know why there is a speed limit.
Here is a similar example with a different context.
Since you like to claim that relativity is "just a theory", let's look at the 2nd LAW of thermodynamics.
The 2nd law basically states that there is a limit to the efficiency you can achieve with a heat engine that produces work. Many kooks have tried to patent perpetual motion machines which violate the limit, without understanding why they can't work. They believe that the theory may be incomplete, or they have discovered some way of violating it, and they criticize scientists that disprove their invention by saying they are just putting faith in the theory and are unable to accept that it may be wrong.
The 2nd law is basically an extension of an observation that has never been proven wrong because it is based on logic -- that heat cannot flow spontaneously from a cold object to a hot object. The reason why this holds true is because of the rules of nature -- when fast moving molecules of a hot object strike slow moving molecules of a cold object, the fast molecules lose energy to the slow molecules. This is based on newton's laws, e.g. momentum transfer of collisions. The fast moving molecules can never GAIN energy by hitting slower molecules. Therefore a hot object can not gain energy from a cold object (without work input). Based on the mathematical statement of this logic, you can derive the 2nd law.
The explanation of relativity and the speed of light works the same way. It starts with a logical premise, which has been proven over and over with observations and has never been disproved -- that the laws of physics are the same in all inertial reference frames. From the mathematical statement of this fact, the relativistic equations which put a speed limit on matter can be derived.
Just because relativity is "only a theory" doesn't mean that it will inevitably be proven wrong at any point. It certainly may be, just like the laws of thermodynamics. We may in the future encounter some situation where conservation of energy is violated, who knows. But since we have countless observations with no disproof of the theory holding true, you have to make a pretty damned good argument to why you think relativity is wrong. [bJust saying "previous scientific theories have been proven wrong in the past" doesn't cut it in this case.[/b]