There’s a lot of doubt about Esther. The book of Esther is not directly quoted in the N.T. It doesn’t mention God. Here’s my contribution to the defense of Esther in the canon.
“Then Mordecai recorded these events, and he sent letters to all the Jews who were in all the provinces of King Ahasuerus, both near and far, obliging them to celebrate the fourteenth day of the month Adar, and the fifteenth day of the same month, annually, because on those days the Jews rid themselves of their enemies, and it was a month which was turned for them from sorrow into gladness and from mourning into a holiday; that they should make them days of feasting and rejoicing and sending portions of food to one another and gifts to the poor” (Esther 9:20-22).
Here’s my thoughts. If you can even find a celebration of Purim (or “lots,” after Haman cast lots to determine the day of the Jews’ extermination, Esther 9:24) in the N.T., this will lend a lot of credence to the authority of Esther. I think I found it. “Those from the peoples and tribes and tongues and nations will look at their dead bodies for three and a half days, and will not permit their dead bodies to be laid in a tomb. And those who dwell on the earth will rejoice over them and celebrate; and they will send gifts to one another, because these two prophets tormented those who dwell on the earth” (Revelation 11:9,10).
"Earth" should be translated "land," as in the rest of the Book of Revelation and in most of the O.T. Prophets.
Three and a half days? Other than the obvious connection to the time between Jesus’ death and resurrection, the events that inspired the Jewish festival of Purim lasted at least three days: “…the Jews who were in Susa assembled on the thirteenth and the fourteenth of the same month, and they rested on the fifteenth day and made it a day of feasting and rejoicing.” (Esther 9:18). This is interesting since Mordecai and Esther, when establishing the celebration of Purim, made it a two-day celebration. The first event, however, for those in the Persian capital, lasted three days.
The ministry and murder of the two witnesses occur in Jerusalem, the Babylon of the Book of Revelation: “And their dead bodies will lie in the street of the great city which mystically is called Sodom and Egypt, where also their Lord was crucified” (Revelation 11:8). Identifying this “great city” as anything other than Jerusalem does damage to the context of Revelation and good interpretation. In our discussion of Purim, it doesn’t matter; Jews didn’t have to be Jerusalem to celebrate this feast. It would have been celebrated throughout the Empire.
I suggest to you that the celebration over the dead bodies of God’s witnesses is the celebration of Purim, explained, established, and mandated in the book of Esther. Just as Purim commemorates the defeat of the Jews’ enemies throughout the Persian Empire, the Purim of Revelation 11:9,10 recognizes the apparent defeat of the Jews’ enemies in A.D. first century: Christians (probably during the first great persecution of the Church under Nero Caesar, the “beast” of Revelation). The witnesses are symbolic of the Church, the witnesses for Jesus in the world (Acts 1:8, and 10 other times in Acts). Why two? Revelation breathes the Old Testament in every verse and idea, including this one: “On the evidence of two witnesses or three witnesses, he who is to die shall be put to death; he shall not be put to death on the evidence of one witness…a single witness shall not rise up against a man on account of any iniquity or any sin which he has committed; on the evidence of two or three witnesses a matter shall be confirmed” (Deuteronomy 17:6; 19:15). Our witness for Christ is a legal matter; it fulfills the requirements of the Law.
I don’t think this conflicts with the other place in the Bible that describes two witnesses. In Zechariah 4, the prophet sees two olive trees beside a great menorah. Twice he is asked if he knows who they are. Twice he says he doesn’t. Then the angel tells him, “These are the two anointed ones who are standing by the Lord of the whole earth” (4:14). They were Zerubbabel (the civil leader) and Joshua (the religious leader). They were used of God to finish rebuilding the Temple in Jerusalem after its destruction by the Babylonians some 70 years earlier. This fits nicely with a preterist understanding of Revelation 11. The Church is the true Temple of God (no new Jewish Temple is foretold in the Bible after the destruction of Herod’s temple in A.D. 70 by the Romans). We now are God’s house. So the Church being the two witnesses doesn’t conflict with Zechariah 4.
On the matter of interpretation, let me say this. A lot of time is spent in N.T. interpretation making the Romans the primary enemy; the Gnostics get a lot of press, too. Here’s the problem. The overwhelming weight of biblical evidence goes to the A.D. first century Jews as being the biggest threat to Christianity. This isn’t racist to say. While a small percentage of Jews accepted Christ as Messiah, a larger percentage greatly persecuted the young Church, including one who became Her greatest apostle: Paul.
“He came to His own, and those who were His own did not receive Him” (John 1:11).
I know I got off track. But just as Reformed Theology is a beautiful Grand Unified Theory that makes the theology of the Bible come together perfectly, Preterism brings the N.T. into a unified focus with the rest of the redemption history of the Bible.
Anyway, there it is: Esther and Purim in the New Testament.
By the way, you know this, but I’ll say it anyway: witness and martyr are the same word in Greek.
 Admittedly, this is faulty because of another example: Hanukah, or the festival of lights. Just because this festival is mentioned in the New Testament doesn’t mean we recognize 1 Maccabees as canonical.
 We have to make an interpretive choice between the two witnesses of Zechariah 4 as our template (and then spent time trying to find two biblical figures like most interpreters do) or look to the N.T.’s use of the word “witness,” which almost exclusively is used of believers.
 And just as a prod to my Dispensationalist brothers and sisters, God isn’t racist or xenophobic, either! Here is His favor and preference for the Jews: Jesus was a Jew and all peoples of the earth (including Jews) can find salvation only in Him. There is “one Body” (Ephesians 4:4). The promises of God to Abraham are completely fulfilled by the giving of the Holy Spirit to disciples of Jesus (Galatians 3:14).