YoYo, what you're doing is putting forth your memory, not of what the Bible actually says, but of what the Watchtower has told you. Let me disavow you of a few notions. I don't have a NWT in front of me so I'll use an online version of the New American Standard Bible.
: There is a pivotal date that historians agree on and that is 539 BCE as the year Babylon fell to the Medes and the Persians (this according to the Nabonidus Chronicle stone).
That is incorrect -- 539 is not in any sense a "pivotal year". It is actually a derived date. Modern historians generally consider only direct astronomically confirmed dates to be in any sense "pivotal", but that term is not generally used today. Look in the Insight book under "Chronology", on page 453, and read the material on exactly how 539 is derived. The Society uses the 7th regnal year of Cambyses as a starting point, from Nisan to Nisan, 523-522 B.C.E. This date is determined by historians from references to two lunar eclipses in certain cuneiform documents. If Cambyses' 7th year was 523/22, then his accession year was 530/29. According to other ancient documents, Cyrus was killed in his 9th regnal year; therefore that must have been 530/29 also. Therefore Cyrus' accession year must have been 539/38. This is one way that historians come up with the 539 date for the overthrow of Babylon.
The Nabonidus Chronicle has nothing whatsoever to do with determining 539, as it contains no information that can be dated to this year. Rather, it contains information that leads to the exact day in some year that Babylon was overthrown, namely, around the beginning of October.
But of course 539 B.C.E. was not originally determined by historians to be the date of Cyrus' accession via the above method, because the necessary cuneiform documents were not discovered until the late 19th century and their contents did not become generally known until around 1890. Before that, historians generally dated Cyrus' accession to 538 or 539 B.C.E. They arrived at the date via several means, the most common one being to start with the accepted date for Nebuchadnezzar's accession, 604 or 605 B.C.E., and then work forward in time using Ptolemy's canon and other ancient sources. The fact that they were either dead on, or off by only one year, is pretty amazing. By the 1940s scholars had published enough information about thousands of cuneiform documents from the "Neo-Babylonian" period (i.e., 626 to 539 B.C.E.) to be able to establish to within a few months at most how long each king reigned in Babylon. The scholars Parker and Dubberstein first published a chart of this material in the mid-1940s. It showed conclusively that Nebuchadnezzar ascended the throne about August, 605 B.C.E. and, working forward through the cuneiform records, that the last king Nabonidus was removed from the throne in October, 539 B.C.E.
Nebuchadnezzar's reign can be confirmed astronomically in several ways. The most common way is to use a cuneiform document that describes a particular lunar eclipse and the positions of various planets on a particular date in Nebuchadnezzar's 37th year. This turns out to be 568/67 B.C.E. Using the charts published by Parker and Dubberstein in their book Babylonian Chronology 626 B.C. - A.D. 75 (1956, 1971), we can go through the reigns of each king succeeding Nebuchadnezzar and get right to 539 B.C.E. as the last year of Nabonidus. Sometime in late 539 or early 538, Cyrus ascended the throne.
So you see, YoYo, the Society has not told you the whole truth about the historical evidence. Exactly the same historical evidence that shows that 539 B.C.E. was the year Babylon fell proves that Nebuchadnezzar ascended the throne in 605 B.C.E. Since according to the Bible Nebuchadnezzar destroyed Jerusalem in either his 18th or 19th year (it's not clear to historians whether the biblical references to these years are using the accession-year or non-accession-year method of referring to Nebuchadnezzar's reign), the destruction must have occurred in either 587 or 586 B.C.E. Note that it is the Bible's ambiguity that is the source of the difference of scholarly opinion here, since no non-biblical documents have been found that indicate the year of Jerusalem's destruction.
: Cyrus was ruler or king at that time. Accroding to Babylonian customs Cyrus' first regnal year would have been from Nisan 538 BCE to Nisan of 537 BCE. Cyrus decreed that the Jews could return to Jerusalem and reestablish themselves there and he gave that decree near the end of 538 BCE or early 537 BCE. Now the trip to Jerusalem from Babylon took about 4 months according to Ezra 7:9. So the Jews arrived Jerusalem during 537 BCE, which was the end of their exile in Babylon.
Actually, scholars these days tend to date the return of the Jews to Palestine to 538, but the evidence is in dispute and it's a minor point that our discussion does not hinge upon.
: 2 Chronicles 36:20, 21 gave the total years of captivity in Babylon as 70 years.
No, it does not. It says that the Jews "were servants to him and to his sons until the rule of the kingdom of Persia", and that "all the days of its desolation it kept sabbath until seventy years were complete." The scripture does not directly equate a period of captivity with a 70-year period, although the language is consistent with such a view.
So just what does 2 Chronicles actually say here? Let's note again what verse 20 says about Nebuchadnezzar and his captives. Note clearly that the passage is specific about until when the Jews served him:
"Those who had escaped from the sword he carried away to Babylon; and they were servants to him and to his sons until the rule of the kingdom of Persia."
This is completely clear: the Jews served Nebuchadnezzar and "his sons" until when? Until the Persians began ruling. When did they begin ruling? In 539 B.C.E., of course.
So according to the Bible, the Jews were no longer considered captives of the king of Babylon and his sons after the fall of Babylon. This passage alone is sufficient to disprove the "chronology" of the Watchtower Society.
We can consider the meaning of "the seventy years" mentioned in verse 21 at a later time.
: Jeremiah 25:11, 12 also prophesied 70 years of captivity."
No, it did not. Again let's see what the passage says without Watchtower blinders on. Speaking not only of the Jews but of all the nations around Judah that were to be made subservient to Babylon, Jeremiah writes in verse 11:
"... these nations will serve the king of Babylon seventy years."
It does not say that all of these nations would be captive, but would serve Babylon for 70 years. This is perfectly consistent with Jeremiah 27, where God tells the Jews and their neighbors to meekly submit to Babylon, and that if they do, they will remain on their land. Jeremiah 27:11 states:
""But the nation which will bring its neck under the yoke of the king of Babylon and serve him, I will let remain on its land," declares the LORD, "and they will till it and dwell in it.""
But if one of these nations refuses to submit, what then? God will punish the nation and desolate it, according to verse 8:
""It will be, that the nation or the kingdom which will not serve him, Nebuchadnezzar king of Babylon, and which will not put its neck under the yoke of the king of Babylon, I will punish that nation with the sword, with famine and with pestilence," declares the LORD, "until I have destroyed it by his hand.""
Now let's see what Jeremiah 25:12 says:
"Then it will be when seventy years are completed I will punish the king of Babylon and that nation,' declares the LORD..."
Note clearly the sequence of events prophesied: First the 70 years will be completed. After that, and only after that, God will punish the king of Babylon.
When was the king of Babylon punished? Obviously, in 539 B.C.E., when the local king of Babyon, Belshazzar, was killed and his father Nabonidus was removed from the throne.
So according to the above scriptures, the 70 years ran out in 539, not in 537 B.C.E. Once again we find the Bible itself disproving Watchtower "chronology".
: Jeremiah 29:10-14 also mentions 70 years.
Indeed it does, and it is perfectly consistent with the above information, which shows that the 70 years were not a period of captivity of the Jews to and in Babylon, but were a period when Babylon would be supreme over the Jews and the nations around them. Whether these nations became captive would be determined by whether they followed what they were told in Jeremiah 27. With this in mind, note what God tells the Jews in Jeremiah 29:10:
"When seventy years have been completed for Babylon, I will visit you and fulfill My good word to you, to bring you back to this place."
Note that the verse indicates that the 70 years were a period related to Babylon, they were "for Babylon", not for the Jews and other nations. This is consistent with what the above scriptures say.
The NWT renders this verse improperly, as "at Babylon". This is easily seen when we examine the internal inconsistency of Watchtower "chronology" here: according to the Society, the Jews were off their land for exactly 70 years, from October 607 to October 537 B.C.E. But they were taken captive to Babylon, which involved some four months to get there and another four months to get back. Therefore they cannot have been captive "at Babylon" for 70 years, but only for about 69 years and four months. So we see that the rendering "seventy years at Babylon" is impossible, whereas "seventy years for Babylon" is consistent with the rest of the Scriptures.
: So if have 537 BCE as the returning of the Jews from captivity and then we go back 70 years, we come to the year 607 BCE as the fall of Jerusalem.
That's the Society's claim, alright, but now you can see why it's wrong.
: Some historians debate on the date of the fall of Jerusalem. Some say it happened in 586 BCE, some in 587 BCE, others say 595/596 BCE and at one time I read that one historian put it at 605 BCE (cannot remember the source though).
Only a few marginal scholars and crackpots put the date at other than 587/6 B.C.E. They do it by completely ignoring the evidence from the Bible along with the virtually unassailable year by year cuneiform records published by good scholars like Parker and Dubberstein. And as I pointed out above, it is only the Bible's ambiguity about in just what year Nebuchadnezzar destroyed Babylon (compare various statements in Jeremiah and 2 Kings about the 19th year with Jeremiah 52:28-30, which mentions the 18th year) that causes the scholarly difference of opinion.
: Anyhow, non of this dates can be taken as pivotal dates, not like the 539 BCE date.
Actually you're wrong. Certain other dates have significantly better substantiation than 539 does. For example, the first capture of Jerusalem in 597 is considered by scholars to be an absolutely secure date, because so many independent lines of evidence point to it. Similarly, Nebuchadnezzar's accession year in 605 is pointed to by starting with his 37th year in 568 B.C.E., an astronomically confirmed date, and working backwards, and by working forwards from another astronomically confirmed date in the period before Nebuchadnezzar's father Nabopolassar began to reign.
: So we are left with the Bible vs. historians.
No, we're left with the Bible and historians versus the Watchtower Society.
: Because I believe that the Bible is the word of God, I favor the Bible's view on the fall of Jerusalem.
Then you should have no trouble accepting what the Bible says about the 70 years, namely, that they ended when Babylon fell, not when the Jews returned to Judah.
: That is why this issue is "an easy one" for me.
It was easy for you. Now that you know what the Bible says, it still should be easy. But dealing with the fact that the Society has been wrong about its fundamental chronology will not be so easy.
AlanF
