Why are the names of the Hebrew calendar months named after the BABYLONIAN DEITIES. Why was it allowed for the Jews during the Babylonian exile to name the Hebrew calendar months after the Babylonian deities, when it clearly states in the Torah not to worship other G-ds besides Hashem.
Why Babylonian Names for Jewish Months? asks this question. The basic answer given is that while the names were originally derived (in part) from Babylonian deities, they have become disconnected from those discarded idols and serve as a reminder of the Babylonian exile. When we lived in the exile, people began referring to the calendar dates by the names that were used by the people among whom they lived. After the end of the first exile, this continued because the major community continued to be in Bavel and those who settled back in Israel were still using it.
Additionally, it is suggested that it is a method of overturning the idol worship and converting it to "normal use" (see below abot Tamuz).
Consider the way we tend to use the current secular names in the world wide calendar nowadays even though they are based on the discarded myths of the Greco-Roman world.
The Jerusalem Talmud5 tells us that the modern names of the months “came up [to Israel] with [the returnees] from Babylon,” at the onset of the second Jewish commonwealth, approximately 350 BCE.6
So, why did we begin to use these names? Why didn’t we stick with the biblical practice of referring to months by their number?
Nachmanides7 suggests that this is consistent with Jeremiah’s prophecy: “Therefore, behold days are coming, says G‑d, and it shall no longer be said [by one who wishes to pronounce an oath], ‘As G‑d lives, who brought up the children of Israel from the land of Egypt,’ but rather, ‘As G‑d lives, who brought up the children of Israel from the north land [Babylon] . . .’”8
The original system was to count months in numeric order, starting from Nissan. Thus, any time a person mentioned a month, he was in effect recalling the exodus from Egypt: we are in, say, the sixth month—six months since the month of the Exodus.9 Thus, the numeric naming served as a constant reminder of our deliverance from Egypt.
After we were delivered from Babylonian captivity, however, we started using the names that we became used to using in Babylon. And now, these names served to remind us that G‑d has redeemed us from this second exile.
6. While many maintain that the names are actually taken from the Babylonian tongue, the Rebbe maintains (Likkutei Sichot, vol. 23, pp. 214ff) that it is likely that many (if not all of) these names are actually Hebrew, but that the practice of calling months by names instead of their numeric position on the calendar originated in Babylon. See also Tammuz—Time for Transformation.
7 Commentary to Exodus 12:2.
8 Jeremiah 16:14.
9 For similar reason, Nachmanides argues, we have no names for the days of the week. Sunday is called “the First Day,” Monday is “the Second Day,” and so on—because we are constantly counting down to the Shabbat. Every time we mention the day of the week—any day of the week—we are fulfilling the divine precept (Exodus 20:8) to always “remember the Shabbat day to keep it holy.”
Why would our sages allow the adoption of the name of idolatry into the holiness of Judaism?
The short answer is that our role is not only to combat idolatry by defacing it, because the psychological motivation that draws people to idolatry is not cured that way. Instead, in the long run, we have to transform the negative psychological proclivities that lead to idolatry and transform them into positive ones. It seems therefore, that the sages’ choice of the name of the false god Tammuz provides us with a case study of the problem of idolatry and its solution.