What judeo-christian and greco-roman values and beliefs support a democratic system?

No taxes ...

One of the main qualities for Greeks was justice, but then again this had a much wider meaning than it does in English. It meant also treating people justly and justifiably. In Greco-Roman law the defendant had the right to guard himself, although deprived of money he was left defending himself. The Greek city states could be oligarchies or a division of the army, or a restricted democracy. Rome started as a kingdom and then turn into a republic - in the first place, aristocratic only but then merchants got voted, and after much widespread anxiety the people were embodied by the Tribune. Furthermore, any Roman citizen could vote, a major concern at that period.