Christianity, at least the current form of Christianity, seems to be a Greek religion with sprinkles of Judaism to give it an air of “authenticity” or “antiquity”. The earliest Christians seemed to have been unaware of The Name: YHWH. Jews never actually say YHWH out loud; they either say “Hashem” (literally “The Name”) or they say “Adonai” which means “LORD”. It’s a recent thing in Christian versions of the Old Testament to actually spell out YHWH with vowels. It thus becomes “Yahweh” for Christians – though saying The Name out loud is extremely blasphemous and highly offensive to Jews.
There are actually two words in Hebrew that mean lord: Adonai and adoni. Adonai is only ever used for the replacement of saying YHWH. Adoni is only used for human beings. In English, and in Greek, we only have one word for “lord”. Greeks would say κυριος or “kyrios”.
In the Septuagint, the Greek version of the Tanach, The Name YHWH is never written. It’s always replaced with kyrios or kyrios theos. Since [Pauline] Christians were Greeks and couldn’t read Hebrew, they used those two words alone for claims of divinity.
In Romans 10:9 – 13, Paul quotes Joel 2:32 (Joel 3:5 LXX) and thinks that the passage says “lord” when it really says YHWH. The entire book of Joel never says the word “lord” at all. It only says YHWH. Here are some other examples of this confusion:
2 Cor 10:17 (quotes Jer 9:42)
1 Thess 4:15 (the word of the Lord [actually the word of YHWH] is a technical expression in OT literature, often referring to a divine prophetic utterance (e.g., Gen 15:1; Isa 1:10; Jonah 1:1; 2 Sam 12:9, 24:11; 1 Kings 13:1, etc.))
2 Tim 2:19 (quotes Num 16:5)
*Not by “Paul”, but according to some Conservative Christians it is:
Heb 1:10 (quotes Ps 102:25-27)
It might be understandable if Paul was Hellenized Jew and didn’t know Hebrew, but it even shows up in 1 Peter 3:10-15 where he quotes Ps 34:12-16. Quite a few scholars say that 1 Peter is pseudopigraphal; this might be one line of evidence. A Hebrew literate Jew wouldn’t make such an error. But “Peter” is a Greek name.
On the other side of things, 1, 2, and 3 John never once quote the Tanach or LXX.