The halls of mandos and elvish "free will"

[Rimbaud]

My argument, such as it is, has as its root the need to distinguish between a deity that perceives the future - a quality I would label, inefficiently, omniprescience - and a deity that defies any thought of linear time and exists in an endless now. Selmo said: "God is not limited to our linear experience of time but exists at all times simultaneously". If this were true, then the moment of creation is as endless as all other moments - all events are for that deity. I am struggling to explain myself. If the deity is not simply 'setting the wheels in motion' but is existent at all times simultaneously then events do not stem from the actions of that deity but rather form partof that deity at any given 'time'.

I'll put it another way.

And thou, Melkor, shalt see that no theme may be played that hath not its uttermost source in me, nor can any alter the music in my despite.

The Music of the Ainur and the above quote both lead to a perception of linear time. Observe "uttermost source". The epic of Middle-Earth has as its foundation, the belief in the ultimate Happy Ending. Melkor's discordant song is therefore a part of the path to that conclusion. If Eru existed in an 'omnitemporal' sense, that ending would not be such, for Eru would be existent at its moment just as truly as Eru is existent still at the moment before Eru started the song - and at any other moment.

So, in the omnitemporal argument, Eru exists simultaneously at both times of 'good' and at times of 'bad'. The latter is not needed to progress to the ultimate good, but is an inherent part of the overall whole, as perceived by Eru.

Since, it seems clear that Tolkien's desire was to make the point that the discordant themes (and the subsequent evil and evil actiobs/events) were necessary to reach the final Good, I would argue that Eru was written as an omniprescient deity not an omnitemporal one.