It is also a Hexagram/Sexagram, which is a symbol the Occult uses, in Freemasonry and other traditions it's called the Seal of Solomon. This fact is often pointed out to smear the symbol, including by myself in the past.
Thing is Satan commonly takes and corrupts Godly symbols. And many of the Christians most determined to use this symbol similarity to smear modern Judaism and modern Israel are all for using the contrived Pillar of Enoch mythology to claim the Pyramid as a Godly symbol.
To start with, claiming the symbol's affiliation with Judaism began with the Rothschild family is simply false, there are known Jewish usages of the symbol that predate the 18th Century (when Mayer Rothschild and his father Moses Baur lived). There is evidence that early Kariates had used it, those are Jews deliberately rebelling against Rabbinic and Kabalistic traditions. The Book Art in Ancient Palestine (can be found on Amazon) documents six pointed stars being found in Archaeological sites in Ancient Israel.
170. Kafr Yasīf III. L. f. Page 326It's popular to imagine the symbol being mentioned in The Bible negatively as the Star of Chiun in Amos 5:26 also called the Star of Rempham in Acts 7:43. I think that reference is about actual worship of the Planet Saturn, (Chiun coming from the Akadian Kawanu, and the Babylonians called it Sukkot/Tabernacle, and Rempham from Repa a Coptic name for Saturn). The Greeks tended to identify the main El the Pagan Canaanites worshiped with Kronos, who was Saturn to the Romans.
The report in Qobeṣ speaks of panels containing doves, serpents, cups, various fruits, a six-pointed star, &c.; intertwined crosses said to be later additions.
172. Khān El Ahmar XVIII. O. t. Page 327
Field: circle within square, the borders interlacing eight times, four times by a simple knot, in corners loops of type I 9. In circle six-pointed star, with trefoils filling the space between its re-entrant angles and the circumference.
Avi-Yonah, M. Art in Ancient Palestine: Selected Studies. Ed. Hannah Katzenstein and Yoram Tsafrir. Jerusalem: Magnes Press, 1981. Print.
But if critics of the Symbol can read it into a Bible verse that just says "star" with no indicator of how many points it's depicted as having. Then a supporter of the symbol can just as validly see it in the Star out of Jacob of Numbers 24:17, a Prophecy that refers first to David but ultimately to The Messiah, Jesus Christ. Or for Christians to the Star of Bethlehem, which we've often linked to the Star out of Jacob.
But what has become interesting to me lately is the Biblical significance of Lilies. Hosea 14:5 uses The Lily as a symbol of Israel in a Prophecy of Israel's restoration. The Song of Solomon uses it of Shulamith. 1 Kings 7:19&22 says the tops of the Pillars of Solomon's Temple were of Lily Work.
Lilies have 3 pedals and 3 sepals that can look like pedals. A Hexagram is a six pointed star that looks like two superimposed triangles. Because of this Lilies can often look kind of like Hexagrams. In fact there is a plant named Solomon's seal (Polygonatum multiflorum) in the lily family. I've even seen in Japanese Anime (like YuriKuma Arashi) examples of lilies looking Hexagram like, where making a Jewish reference was not likely the Author's intent.
So maybe The Lily is the key to figuring out where the Star of David/Seal of Solomon came from?
Update January 30th 2017: Okay, one element of this I originally didn't want to include is how people say this has something to do with the Number of the Beast. But I decided I should address that.
The Number of The Beast from the last verse of Revelation 13 is Six Hundred and Sixty Six. Not Six-Six-Six. So no, not every usage of the number 6 is about the Mark of The Beast. And that is all that should need to be said to refute that absurdity.
Six is a number that is used positively sometimes in Scripture. 12 and 24 and 72, and 144,000 are numbers that are multiples of Six. The Sixth day of a Biblical Week was the preparation day for The Sabbath. Which was the day Jesus was buried.
Adam was created on the 6th Day, Jesus is the Last Adam, and that some symbolism linkable to Adam will be taken by The Beast is only because The Beast wants to claim titles of Christ for himself.
Update May 2017: My defense of Jews and Christians using it doesn't mean however that I think it's won't be used by The Antichrist in an End Times deceptions. I talked recently on my Prophecy Blog about the Ring of Solomon. This symbol isn't what the Mark of the Beast is, but it could still become part of how The False Prophet packages it.