"Jerusalem has Sinned a Sin..." (Eicha 1:8)

In Megilas Eicha (the Book of Lamentations) we read (1:8):

חטא חטאה ירושלים על כן לנידה היתה וכו'

"Jerusalem has sinned a sin, therefore she has become a wanderer..."

(The translation of נידה as "wanderer" follows Rashi and Targum. Homiletically, it can also be understood as referring to a "niddah" - a menstruant woman, who is forbidden to her husband until she undergoes ritual purification.)

Many commentaries note the repetitious language of the opening words in the verse, "חטא חטאה ירושלים" - "Jerusalem has sinned a sin" - and a wide range of homiletic interpretations are given for this language.

The Chida

The Chida (Rav Chaim Yosef David Azulai, d.1806), in his commentary Nachal Eshkol, gives nine interesting and illuminating explanations for the repetitious language of the verse. In most of these commentaries (the exceptions being the last two), the Chida interprets the double language either as indicating a "double sin", or as indicating that, despite some argument to minimize their guilt, nevertheless, their act was indeed a sin. It should be noted that some of explanations rely on rather obscure Kabbalistic concepts:

1. While, with regard to most sins, one is only held liable for the actual sinful act, with regard to the sin of idolatry one is held liable even for the thought of sin. Thus, when the Jewish people committed the sin of idolatry, they were held liable for a "double sin" - a sin of thought and a sin of deed.
2. The guilt of one who commits a crime in the palace of the king is far greater than that of one who commits a crime outside the immediate presence of the king. Jerusalem is the "palace of the king", and a sin committed within Jerusalem carries a double burden of guilt.
3. The Shechina (Divine Presence) rests in Jerusalem, and the land itself is holy. These factors should have a powerful influence on us to help us avoid sin and to serve God properly. To sin in such a environment therefore carries a double portion of guilt.
4. Rav Chaim Vital (d.1620) taught that saying that one does not wish to give tzedaka (charity) is considered a sinful act. Thus, the Jewish people indeed sinned by saying that they did not want to give tzedaka. (The Chida's intent here seems to be as follows. One of the sins that led to the churban (destruction) was the failure to give charity (Targum on Eicha 1:3). However, in of itself, the failure to give tzedaka is simply a failure to fulfill a positive obligation and should not be sufficient to bring about such a punishment. However, from Rav Chaim Vital we learn that if one explicitly states that he does not wish to give charity, this is considered a sinful act akin to idolatry. Thus, they indeed actively "sinned a sin.")
5. The Sages comment on this verse (Eicha Rabba 1:35):

   חטא חטאה ירושלים - אומות העולם אינן חוטאים? אלא אע"פ שחוטאין אינן כלום, אבל ישראל חטאו ולקו 

   "Jerusalem has sinned a sin" - [And] the [other] nations of the word don't sin? Rather, even though they sin, it is insignificant, whereas [when the people of] Israel sin, they are punished.

   What is the justice in this? Why are the sins of the Jewish people considered so much worse than the sins of the nations? The answer is because God took us out of Egypt, gave us His Torah, performed great signs and wonders for us, and gave us the land of Israel, all for the purpose that we should obey His laws. Thus, the Jewish people are held to a higher standard and their sins, even those that would be of no significance with regard to the other nations, are indeed sins.
6. Alternatively, we can understand this medrash based upon a concept found in the work Chesed L'Avraham (a major Kabbalistic work written by the Chida's ancestor, Rav Avraham Azulai, d.1643) that, from the generation of the dispersal (resulting from the Tower of Babel), the sins of the non-Jewish nations only damage the "prince" (i.e. angel) assigned to that nation, whereas the sins of the Jewish people cause damage to the highest "attributes." Thus, the sins of Jewish people bear of double portion of guilt. At the same time, however, the fact that the sins of the Jewish people cause damage on such a high level also means that they can be rectified (the Chida does not explain exactly why this is so). Thus, "Jerusalem has sinned a sin" (i.e. the sins of the Jewish people are considered significant) "therefore she has become a niddah" - a menstruant woman - whose separation from her husband is temporary.
7. If a person sins unintentionally twice, it is no longer considered an unintentional sin. (The Chida states that we learn this from the second perek of Beitza, presumably referring to Beitza 16b, where we learn that one who twice forgets to make an eruv tavshilin is considered a poshea (negligent) and cannot rely on the eruv of the local rabbi.) Thus, the verse says that even if Jerusalem sinned unintentionally, because of repetition the unintentional sin bore the full weight of guilt of an intentional sin; it was indeed a sin.
8. The prophet Micah (4:6) said about the time of redemption:

   ביום ההוא נאום ה' אספה הצלעה והנדחה אקבצה ואשר הרעותי. 

   "On that day, says God, I will bring in the lame one, and the one who was driven away I shall gather, and the one I have harmed.

   On this verse the Sages comment (Shemos Rabba 46:4), מהו 'אשר הרעותי'? זה יצר הרע - "What is the meaning of, 'the one I have harmed'? [What harm does this refer to?] This refers to the yetzer hara - the evil inclination." God placed the yetzer hara within every human being to tempt him to sin. Thus, so to speak, on a certain level, God acknowledges that the sin of Jerusalem is His "fault". Thus, we can read the verse, "חטא" - "Sin," i.e. the yetzer hara (the term חטא can be understood to refer to the yetzer hara, as we see in Genesis 4:7), "חטאה ירושלים" - "caused Jerusalem to sin." This reduces their guilt,  "therefore she has become a niddah" and will be purified and return to her Husband.
9. The intentional sins of a צבור - community - are considered as unintentional. (כמ"ש הרב כתנות אור פרשת נצבים) Thus, the sins of Jerusalem are to be considered unintentional sins. (While the term  "חטא" is a generic term for sin, in some contexts - such as when used in combination with other terms for sin - it can have the specific connotation of unintentional sin. In this commentary, the Chida apparently interprets the double language to indicate an emphasis on the specific language of  "חטא" with its connotation of unintentional sin.) Thus the verse says, "Jerusalem has sinned an unintentional sin, therefore she has become a niddah" and will be purified and return to her Husband.