The Bach oratorio is off topic in any case, I do not feel the need to provide you with further explanations. I suggest we return on topic to the matter of Messiah.

Ah, but the best part of the text there to my mind is:

Their land brought forth FROGS,
Their land BROUGHT forth frogs,
YAY!
Even in their King's chambers...

Or something like that.

The drama in pieces like Belshazzar, Hercules or Jephtha is simply magnificent as far as I'm concerned. Of course they do different things from what Messiah was aiming at: stories, characterisation, that sort of thing. I had typed 'opera in all but name' - but in fact the oratorio form let him do things which opera wouldn't have allowed, in particular when a chorus can reflect on the action. And he could write a decent chorus when he wanted to.

How dark, O Lord, are thy decrees
   All hid from mortal sight!
All our joys to sorrow turning,
And our triumphs into mourning,
   As the night succeeds the day.
      No certain bliss,
      No solid peace,
      We mortals know,
      On earth below-
   Yet on this maxim still obey.
      Whatever is, is right.

Concert performances of dramatic works, especially operas, are common enough but it doesn't often happen the other way round, does it? One example I can think of is Sullivan's The Martyr of Antioch. Although it was called a "sacred musical drama" it was only ever intended to be performed in the manner of a cantata or oratorio. But the Carl Rosa Opera Company made an opera out of it, with costumes, scenery and action, to the surprise of the composer.

And I take Don Basilio's point about oratorios allowing Handel to do things that wouldn't have been possible in opera. But would I be right in thinking that an opera about Jesus in those days just wouldn't have been allowed, or at least would have been considered to be in bad taste?

Quite so. Or rather the whole history of salvation, conveyed through allusive texts.  (I've said it before, but Charles Jennens choice of texts for Messiah is very clever.)

 But there is an exact point where you can compare Bach and Handel, in that they both set the Annunciation to the shepherds, preceded by a siciliana-style pastoral symphony.

At that point Handel does it better: after all he had dramatic sense and had written more operas than many have had Christmas dinners.

I'm rather suprised to find that I am beginning to realise I like Bach!

If Pasolini can do a movie of the Gospel according to Matthew (with the Annunciation from Luke, but he was an Italian bachelor so he could hardly miss out the Madonna) I don't think there would be any objection to an opera per se.

ENO did a staged Verdi Requiem, too (2000) and A Child of Our Time (2005).

The Verdi was critically panned, but I found it one of the most powerful pieces of theatre I've ever seen.

Jurst about on topic I hope, and prompted by Don B's comments on Bach's and Handel's settings of the annunciation to the shepherds, two of my Christmas highlights this year were performances of Schutz's The Christmas Story and Messiaen's La Nativite du Seigneur. Was I deluded in thinking that Messiaen's Journey of the Magi contains a direct-ish reference to Schutz's treatment of the same passage? Or is it simply that neither could resist including the rolling gait of camels?  I don't have a recording of either piece to check up.

I have never disliked Bach.  But I realise that trained musicians can appreciate subtleties that pass me by, and I suspect it may be beyond me.  I might start a thread if I feel brave.