Vergere was actually a sith though and was basically lying to Jacen Solo the entire time which is ultimately what lead to him become a sith in the same fashion as his grandfather.
It has been made pretty clear that the idea of the Unifying Force which was put forth in The New Jedi Order was all phooey, and that the force truly has both a light and darkside.
Way to derail the thread... j/k
. But when you get down to it, this discussion could get as in depth has real life theology. I prefer the belief that it doesn't have a "side", and it's how you use it that counts. Kind of like a gun, it can be used to murder people but it could also be used to protect people.