Earnest : So, for some reason which is open to debate the name of God was removed from the Christian LXX
jhine : The removal of the Divine name in all of the [NT mss] copies made...would have had to have been a huge undertaking .
Yes. I expressed myself badly. I didn't mean that the name of God had been removed from the copies of the LXX in which it already existed. Or from NT mss in which it existed (if it did). I meant that at some time during the first century, probably after the destruction of the second temple, God's name was replaced with the word 'Lord' in subsequent copies they made.
So, in LXX mss prior to the second century C.E we do find the teragrammaton and the Greek equivalent. After the first century we do not. As we have no NT mss prior to the second century we cannot say whether they followed the same pattern but it is reasonable to think so. As Dr Paul Kahle said 58 years ago (The Cairo Geniza, Oxford, 1959, p. 222),
We now know that the Greek Bible text [the Septuagint] as far as it was
written by Jews for Jews did not translate the Divine name by kyrios;
but the Tetragrammaton, written with Hebrew or Greek letters, was
retained in such MSS.
So, in the time that the Gospels and letters were written by Jews for Jews it seems likely that they followed the same pattern. As Paul was the apostle to the Gentiles I am less sure of him, although the letter to the Hebrews would surely be an exception. Also, if he was quoting from the LXX I would not expect him to change it.
There are indications that there was some control in copying the Christian scriptures. One notable effect are the sacred names referred to earlier, where 'Lord' and 'God' and several others are abbreviated. This happens in all early Christian mss, but not in Jewish mss, so you can tell whether a copy of the LXX is Jewish or Christian. Another effect is that books (codices) were used instead of scrolls. This, again, is identifiable as Christian. Universally. So it is quite feasible that it was decided that kyrios would replace God's name. The reason may be, as Kahle suggests, that "the divine name written in Hebrew letters was not understood any more." It was not necessarily a Satanic plot. It could have been that they simply wanted to distinguish themselves from being a Jewish sect. I don't know. But I'm pretty sure it happened.