The bitterness of party struggles in Greece during the Peloponnesian War meant that in many states they became a threat to local constitutions, and to democratic institutions.
Aristotle mentions (Politics, p. 1310 a) a secret oath taken by the members of oligarchic clubs, containing the promise, "I will be an enemy to the people, and will devise all the harm I can against them."
At Athens, the Athenian coup of 411 BC, a conspiracy against their democracy was engineered, in part, by these clubs, which existed there and in the other cities of the Delian League (Thuc.
There were clubs supporting the cults of foreign deities such as Sabazius, Mater Magna (see Great mother of the gods) and Attis, Adonis, Isis, Serapis, Men Tyrannos.
The members of these religious clubs included women, freedmen, foreigners and slaves but rarely people who held citizenship by birth.
An inscription found by Sir Charles Thomas Newton at Cnidus contains a mutilated list of members of a thiasos includes apparently only one Cnidian citizen out of twelve, four slaves, and probably seven foreigners.
The clubs had laws, an assembly and magistrates or officers (typically epimeletai, a tamias (treasurer) and a grammateus (secretary)), as well as priests or priestesses, and organised finances.
Rules regulated the conditions of admission, which involved an entrance fee and an examination as to character; the contributions, payable by the month, and the steps to be taken to enforce payment, e.g. exclusion in case of persistent neglect of this duty.
Rules also governed the use to be made of the revenues, such as the building or maintenance of temple or club-house, and the cost of crowns or other honours voted by the assembly to its officers.
[3] Religious clubs increased in number and importance in the later periods of Greek history, and a large proportion of the inscriptions relating to them belong to the Macedonian and Roman empires.