The original language allows us to see the meaning in relation to other possible meanings. For example, both "ordain" (τάσσω) and "prepare" (ἑτοιμάζω) are used in the original New Testament. One can arrive at the proper meaning by observing which is used and, as in the case on hand, Eph. 2:10, which is not used, but the Protestant translation would cram it in there anyway and hope no one will notice.
However, deriving theology from the scripture alone is an absurd proposition, as not every possible error of man is similarly anticipated.
Right, they are a result, or rather a consequence, of an ambigiuous verse (Rom 5:12) which can be correctly read in two different ways. So, right there goes the idea that the scriptures inherently have a clear meaning (even in the original language).
The original language allows us to see the meaning in relation to other possible meanings. For example, both "ordain" (τάσσω) and "prepare" (ἑτοιμάζω) are used in the original New Testament
I didn't follow the discussion you had with Dr. E vis-a-vis Eph 2:10. But I would like observe that the same προετοιμάζω which in KJV Eph 2:10 reads as "before ordained" is translated in Rom 9:23 as "afore prepared".
What we have here is an example of two different English words, with distinctly different meaning ("ordain" carries the weight of a decree; "prepared" doesn't.), created by the translation out of one and the same word in the original.