It is much said about this ancient symbol whether it is a symbol of good or evil. What does this star has to do with King David?

It is neither good nor bad it is just a symbol most closely associated
with the religion of Judaism. There is a whole Wiki article which
describes it's history here:

http://en.wikipedia.org/wiki/Star_of_David

It has it's own unicode ascii character ✡

You might as well ask if the symbol of the cross † is good or evil.
It is just a symbol most closely associated with Christianity but
it has been used in history to symbolize good things like churches
and Christ and bad things like the KKK.

The symbol itself is neither good or bad it is just a symbol.

Same thing for the pentagram. It is closely associated with Satanism
but really it is just a 5-pointed star. ★

You might as well ask if an asterisk *, ampersand & or caret ^
are good or evil.



They are neither. ☑

It does have an interesting History!
The Jewish Brigade in WWII used it as an Insignia and Shoulder-Patch!
http://en.wikipedia.org/wiki/Jewish_Brigade