The earliest known writing in Hebrew, Phoenician alphabet, dates from the 11th century BC. Which means that King David, who lived in the end of that period, read and wrote these letters.
The first evidence of this script is Gezer Calendar, which dates to around the 10th century BCE and records agricultural activities throughout the year.
Israeli Researcher Uri Ofir mentions a theory
which is found in the literature, that King David adopted this form as his emblem because of its special form which fitted his name. In ancient Hebrew (Daatz writing) the letter "d" (dalet) was written in the form of a triangle and in the name David there are two triangles (two characters of d).
James Lloyd is one of the opponents of the one of the worst opponents in general and of the above-mentioned theory in particular. In an article titled Damage Control: Defending The Star Of Satan? Published on October 4 2005 he says:
However, those that refuse to repent from their apostasy in the Christian church (read Babylonian whore church) today have produced an argument that can best be described as damage control. It provides no historical references, no anecdotal data, no footnotes, and a couple of very contrived scriptural references. It goes something like this:
In the Hebrew alphabet, the letter for the letter "d" is called a dalet, and it looks triangular. Since David's name had 2 dalets in it, the ancient Israelites used two dalets, with one of them turned (which would loosely approximate a hexagonal star), to represent that they were the armies of David.
There is no scripture that states this. There is no archeological find that states this. There is no Jewish commentary that states this. There is no ancient inscription in any language, country, or era that states this. There is no historical reference of any kind from any nation that knew of this supposed connection. In short, it's pure speculation. Damage Control.