[Child of the 7th Age]

These passages do have a far more explicitly Christian outlook. The broad questions and points that appear in the Athrabeth Finrod ah Andreth clearly relate to Tolkien's own Catholic background. If Middle-earth is the early phase of our own world, which Tolkien indeed maintained, then the ideas in the Athrabeth point towards the very distant future (not the future of our contemporary world, but that of Middle-earth itself) when, according to Tolkien's beliefs, the Incarnation would occur. With these passages, Tolkien extends his time line far beyond Middle-earth into our own historical world.

In his commentary, Christopher Tolkien comments on the quotations which you've put forward (p. 335). He says that Finrod's statements about having Eru be both "inside" and "outside" the World in effect suggest the "possibility of complexity or of distinctions in the nature of Eru, which nonetheless leaves him 'The One'". Tolkien's discussion of inside and outside thus prefigures the concept of the Trinity and how Christ would come not to Middle-earth but to our own historical world. In the same way Tolkien referred to another "theological" event in Morgoth's Ring -- the fall of Man -- as depicted in the Tale of Adanel.

The passages you quote do relate to the fate of Morgoth, but only indirectly I believe. As a traditional Christian, Tolkien believed that all of history was inevitably a series of defeats punctuated with small, temporary victories, and that final victory was not possible until the end of time. So in that sense, your suggestion is correct. In Tolkien's view, there can be no final defeat of Morgoth or his minions, or the cleansing of the stain on Arda, until that end of time comes about. And undoubtedly Tolkien would have seen the actual Incarnation (the references to Eru being both inside and outside Arda) as an essential ingredient in that respect.

BTW, I've always found these final writings of Tolkien to be fascinating for any number of reasons, including the whole question of what happens to Elves at the end of time, how Men viewed their own situation when compared to that of the Elves, and the personage of Andreth herself. I had put up another thread on Andreth and Adanel some time ago, and have bumped that forward now to see if anyone has any more comments to add to the discussion.