One thing that stands out as questionable is the Spartan King Leonidas invoking faith and reason. This would have been more accurate coming from an Athenian than from the leaders of an autocratic state like Sparta. But while individual freedom was not a Spartan principle, the notion of independence was. Sparta stressed its own independence and freedom from outside rule or domination, so its unified, regimented society was felt to be necessary to maintain that freedom.
Even more important, Spartan warriors were critical to saving Greece, which, as a whole, was indeed the seat of reason and freedom in the world at the time.
Without Thermopylae, the Spartans, and the victories that followed the West would never have been able to create the most successful and creative civilization in history. Periodically the West has had to fend off barbarians like the Persians, the Muslims in the 700s in Spain and France, the Mongols in the 1200s and the Muslims again as late as 1683 at the siege of Vienna. The question now is are we united and inspired enough to repel the Muslim terrorists who threaten us today.
300 shows a unified warrior people defeating (ultimately) a benighted, aggressive invasion. Where are the warriors among us today?