“Since the Eleans were becoming a numerous people and were governing themselves in accordance with law, the Lacedaemonians viewed their growing power with suspicion and assisted them in establishing a settled mode of life for the community, in order that they might enjoy the benefits of peace and never experience the activities of war. 2 And they made the Eleans sacred to the god,1 with the concurrence of practically the whole Greek world. As a consequence the Eleans took no part in the campaign against Xerxes, but they were relieved of service because of their responsibility for the honour due to the god, and further, in like struggles, when the Greeks were warring among themselves, no state caused them any annoyance, since all Greek states were zealous to preserve the sanctity and inviolability of the land and city. Many generations later, however, the Eleans also began to join in campaigns and to enter upon wars of their own choosing.
The Eleans took no part in the wars in which all the rest of the Greeks shared. In fact, when Xerxes advanced against the Greeks with so many myriads of soldiers, the allies relieved them of service in the field, the leaders instructing them that they would be returning a greater service if they should undertake responsibility for the honour due to the gods.”
The proposed meaning of Bellerphon being "Slayer of Beliar" I think also fits Josiah better, who specifically stamped out the worship of Baal.