The DSS have revealed many things:
- They show that the text of the MT (the basis of the OT text in modern translations) contains redactions and scribal corrections; the same is true with the DSS themselves (as there are multiple copies of each book in the Qumran library).
- They show that often when the LXX departs from the MT, it isn't because of mistranslation into Greek but that the Greek contains readings found in the underlying Hebrew text. Often but not always these readings are superior to those in the MT (which dates to much later).
- They show that different editions of books circulated in antiquity. We already know this already from the LXX (which contains different editions of Esther, Daniel, and Ezra-Nehemiah from what is found in the MT), but one could conjecture that the books were altered when they were translated into Greek. The DSS shows that 1-2 Samuel, Jeremiah, and the Psalms circulated in the Hebrew in quite different editions than what is found in the MT, and contain many of the differences also found in the LXX. In many cases, it is the MT that appears to redacted (e.g. comparing the LXX, Josephus, the DSS, and the MT, one can see the height of Goliath in cubits grow taller and taller as time goes on). In other cases it is the DSS text that is innovative (e.g. in some scrolls the first four books of the Pentateuch are interpolated with material from Deuteronomy, in much the same way as the Samaritan Pentateuch does). In certain instances, the specificity of information found in the MT of Jeremiah is missing in the older LXX and DSS, revealing a redaction history to the wording of the prophecies. The Qumran Psalter shows that the order of psalms could vary and that additional psalms could be included. The Society likes to mention the Great Isaiah Scroll as proof that the MT is accurate, without acknowledging that this is not representative of other books in the OT.
- They show that the canon of the OT in the first century BC and the first century AD was not necessary the same as what we have in our Bibles. Our modern (Western) Christian OT canon is identical to that of the Jewish Tanakh, which derives the canon of the second-century AD rabbis, which in reflects what the Pharisees thought their canon to be. Jerome, who translated the Vulgate, advocated the canon of rabbinical Judaism as the "true" canon. But earlier Christian writers, such as the Tertullian, and the authors of Jude and Barnabas, had other ideas of canon and recognized as inspired and/or scripture books not found in the rabbinical canon, such as 1 Enoch and Jubilees. To this very day these two books are still canonical in the Ethiopian Orthodox Church. The DSS shows that there were other Jewish canons in antiquity, and the Essenes considered books like 1 Enoch and Jubilees to be canonical scripture as well.
- The DSS show that the content and form of 1 Enoch has changed over time. The version still used by the Ethiopian Orthodox Church had been translated at least twice (from Aramaic into Greek, from Greek into Ethiopian) and it contains the Book of Parables; the DSS attest the original Aramaic text and thus eliminate many corruptions to the text. The Book of Parables is not found at all in the copies at Qumran, which indicates that it was a later addition (written probably early in the first century AD). The Book of Luminaries, located between the Book of Parables and the Book of Dreams in the Ethiopian text, meanwhile, circulated as an independent (and longer) book at Qumran. The Book of Giants also circulated at Qumran but it was not included in the Ethiopic version of 1 Enoch (but it turns up in a later edition in the Manichaean scriptures), it is possible that the Book of Parables replaced it.
- The DSS contain other stories and visions of Daniel and what likely are sources to the canonical book of Daniel (which was completed around 164 BC). The Prayer of Nabonidus (PrNab) is likely a more original and more historically accurate story than ch. 4 of Daniel, and the Book of Giants and the Book of Watchers (third century BC) contain throne visions that ch. 7 of Daniel follows almost word for word. There is an account of the acts of Antiochus IV Epiphanes that is possibly a source for ch. 11 of Daniel.
- The DSS contain the use of the tetragrammaton in the OT, often in paleo-Hebrew characters that would be unfamiliar to one who reads only the contemporary Aramaic-style script. We know that the scribes who copied the scrolls pronounced these characters as "Adonai" (Lord) and not as a vocalization of the tetragrammaton itself (such as Yahweh or the modern Jehovah). We know this because of notations and errors made in the Great Isaiah Scroll; sometimes a scribe would mistakenly write "Adonai" instead of YHWH and sometimes the reverse would happen. There are many other scrolls that quote from the OT but substitute "Adonai" for YHWH. This undercuts the Society's claim that YHWH necessarily appeared in the originals of the NT when the OT was being quoted, for the Qumran scrolls do indeed contain the tetragrammaton in the biblical texts. And the behavior of the scribes at Qumran also suggest that even if the tetragrammaton had appeared in the originals of the NT, it would have probably pronounced as "Lord" (Paul himself indicates in several places in Romans that he considered the name as "Lord"). But an OG fragment of Leviticus in the DSS also indicates that the name was also vocalized (there as Iαω) in some verisons, so the question of whether a vocalized form of the tetragrammaton was original to the OG/LXX is a matter of continued debate.