Who are the Children of Ilúvatar?

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The usual answer is Elves and Men.

But the correct answer is Elves, Men, Angels (Maia) and the Valar including even Melkor/ Morgoth and Manwe.

These are all the same species or kind, evidenced by the fact that they all look pretty much the same - varying mainly by size - and can interbreed. 

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So the Maia are known to be lesser than the Ainur, but of the same kind - and the Maia Melian married and had a child with the Elf Thingol; their half-Maia half-Elven child Luthien had a fertile marriage with Beren; and there were Elf Human marriages between their descendants including Idril and Tuor, and Arwen and Aragorn. 

Furthermore, there was at least one probable recorded marriage of a Silvan Elf and a Prince of Dol Amroth. 

So clearly Men and Elves and Maia were of the same kind, and Maia are Valar - so all of these are, it seems, Children of Iluvitar. 

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Only the primary creator God (the One, Illuvatar, Eru) is set apart as a being of different kind, and outside of the world...

But wait! If we go back to the Lost Tales to try and recover Tolkien's original conception and image of the nature of Illuvatar; in The Music of the Ainur (the Ainur being the senior Valar) we find:

"Behold, Illuvatar dwelt alone. Before all things he sang into being the Ainur first, and greatest is their power and glory of all his creatures within the world and without. Thereafter he fashioned them dwellings in the void, and dwelt among them, teaching them all manner of things, and the greatest of these was music."

And dwelt among them! 

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So, by joining and building these speculative inferences; it seems to be implied, or perhaps simply assumed, that The One, Illuvatar/ Eru is also man-like - God with body, parts and passions!

So, the Father of the Children of Illuvatar is of the same kind as His Children.

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Of these various beings, it seems that only Men are 'mortal', in the sense that at death their spirits leave the world of the 'dwellings' that were fashioned in the void for Valar and Elves; thus Men are only visitors to these dwellings in the void. 

After death, it seems, Men's spirits leave these dwellings in the void and go to where Illuvatar also dwells; and this can be seen as a higher destiny for Men.

Men are the same kind as Illuvatar the creator and Father, and share his dwelling after death; and the Children of Illuvatar (Valar, Elves and Men) are a chain of familiarly-related beings, a 'Heavenly' Father with sons and daughters... 

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The saddest thing about all this is that the family seems to be sundered - with Elves and Valar remaining in the world while Men and Illuvatar will gather outwith that world.  

So, the greatest hope of universal salvation is for a New World, an Arda Remade, where all the Children of Illuvatar can come to dwell again together - as indeed was prophesied, or hoped-for, by Finrod:

http://charltonteaching.blogspot.co.uk/2008/09/tolkiens-marring-of-men.html

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