First off, I looked at your blog, congrats! on the new munchkin. Now on to my post!
You said:
Simple. No one, save God, knows who the elect are. This is why we go to every area of the world to share the gospel--to harvest that which He has planted.
Secondly, as to your taking tassw (its inflected form) as middle in verse 48, I don't think you can do that. Certainly context is an issue but, here especially, I think the context argues against you.
Luke is making a definite distinction between the Jews (the "chosen" people) and the Gentiles (the "un-chosen" people). Luke goes out of his way to show the rejection of the "chosen" and the acceptance of the "unchosen." I think he's doing this so that his reader will understand that this is God's doing this--choosing people from the unchosen.
When you take into consideration the Jew's common understanding that they were "Chosen by God" as His special people, I don't think your argument works.
Secondly, the most natural meaning of tassw is passive. Really, who would "appoint one's self?" If you appoint, that is active and requires a direct object. If you are appointed, it is passive. It is highly unlikely that anyone appoints themselves (in the manner in which the root meaning of tassw speaks). So, the argument for a middle-voice understanding is quite weak based on natural the most natural meaning of the word itself. If you put that together with the contextual consideration I pointed out above, along with the entire context of scripture, it is difficult to take this to be other than a passive.
Many blessings to you and your growing family,
The Archangel
Edited for many super-annoying, little typos, I need to proodfeed better.....see! There I go AGAIN!