Dionysus is the god who, in myth at least, brings madness and upsets social order. He is really not like any other Greek deity.
For a long time, scholars thought he was a foreign deity. But some form of Dionysus is known to the early Greeks as evidenced by the Linear B tablets. His cult nonetheless seems influenced by Near Eastern cults - the ecstatic dancing of the Phyrgian Cybele, the notion of dying and reborn vegetation gods that exist in Semetic cultures and (most especially) the Osiris cult from Ancient Egypt.
It has been said Dionysus is a native Hellenic god in whom The Foreign or The Other is embodied. In myth, his presence inspires people to step outside their normal selves and their normal roles. The most extreme example of this is his group of female followers, the Maenads. They frolicked in the countryside and in the mountains, and were said to tear animals apart (and sometimes humans) with their bare hands while they were in a frenzy.
I'm not an expert scholar on the Maenads and I am not sure how much evidence there is of supernaturally charged women actually doing that sort of thing. Regardless, that's not what this post is about.
What is true is that Dionysus by his very nature appealed to areas of life and to areas of society not sanctioned by normative society. His cult did appeal to foreigners, to women, and to those seeking escape of social constraints. If the authorities of Ancient Greece sometimes viewed his cult with suspicion, in later times the authorities of the Roman Republic would have a severe reaction to this sort of thing. (Ah, but we're getting ahead of the story...)
There are a few avenues of "madness" we need to discuss.
The first is the most well known. Wine, and intoxication. Dionysus is the god of wine - and by extension all alcohol. Mead was probably known before wine, but it wasn't extremely widespread in Greece. And the Greeks knew that fermenting cereal grain produced beer (the Sumerians had been doing this for centuries), but they generally considered this a barbarian drink.
Dionysus was the god of grape and wine. And became the patron of those who cultivated the vine. The Greeks created a heavy wine syrup which they then mixed with water to dilute the alcohol. The grape grew very well in the Ancient Mediterranean and wine quickly became the staple to drink.
Drunken parties were certainly known, then as now. There is more than enough art work showing young males having drunken orgies. And yet, in polite society, habitual drunkenness was frowned on, as I alluded to in my first post on Dionysus. But nonetheless we can say that wine, in moderation or otherwise, certainly inspired a person to step outside of their normal selves.
The second method was ecstatic dance and music.
The cultists of Dionysus formed processions called dithyrambs. These processions told the mythology of Dionysus and particularly his tragic birth (of which there were several versions). They seemed to be a somewhat riotous affair of dance and music and perhaps inspired by the processions of the Anatolian Cybele.
These cultic processions would soon produce a new art form - theater. Theater soon captured the imagination of the Greeks and in particular the Athenians. Theater became a new art form in which both performer and audience can safely experience a form of madness, a stepping outside of oneself.
And that will be the subject of the third post on Dionysus.