That's simply in response to the demand from the evos that creationists/IDers provide *scientific evidence* to support their side.
They are challenged that there is no proof (evidence) and challenged to provide something a scientist would accept. And when they do, what happens? Just what happened in this post.
The sneer that we think our belief system is in someway provable is unjustified because there are many evos here on this forum who think that evolution has been proved to the point of considering it able to be called a fact.
Scientists themselves think that their belief system is somehow provable, otherwise they wouldn't keep referring to the *mountains of evidence* to back up their claims. They also make allusions to logical points and supposed scientific studies, and not all scientific studies meet the rigor they are supposed to, even if they do not contain outright fraud.
It is at this point that you slip off the path.
Scientists do not think that their belief system is provable. They think it is discoverable. And they are perfectly willing to modify their beliefs as further evidence materializes.
They are not the hide-bound stubborn jackasses you may think they are. They just like saying "prove it!", even to each other.