is the most peaceful philosophy
Jesus said "blessed are the peacemakers" and "turn the other cheek", but you don't seem to judge Christianity by the ideals of its founder alone. Rather, what you're interested in is how a religion pans out in practice. So then, let's take a cursory glance at Buddhism history.
Premodern Japan had prominent Buddhist monasteries such as Enryaku-ji and Mii-dera, which were independent fiefdoms that collected rents from peasants and were backed by sohei (a caste of warrior monks). These sometimes waged wars of aggression against secular fiefdoms or against each other on account of theological differences.
The practical dynamics at play largely resembled those in Medieval Europe or the fire temples of Zoroastrian Iran, where pious nobles made donations of land to monastic institutions, which over the course of centuries often managed to accrue vast landholdings. Their power was only curbed by the warlord Oda Nobunaga at the end of a long struggle to unify the politically fractured country.
And if that was true in Japan, then we can assume it was probably true in other East Asian/Southeast Asian countries as well.
Indeed, we can assume Southeast Asia (where Theravada as opposed to Mahayana Buddhism dominated) was probably even less egalitarian-minded. The Theravadin suppose that only a small elect, not the laity, are sufficiently self-controlled to achieve salvation. All laypeople can really do is hope that they'll be reincarnated one day as somebody who becomes a monk, and tread water (re: not accrue more bad karma and end up in a non-human body) in the meantime by earning merit.
And how does a Theravada layperson earn merit? By supporting the livelihood of the elect. It is a feature, not a bug, of Theravada societies that the many live to serve the privileged few. This takes the form of public, socially sanctioned rituals.
Finally, let's examine Tibetan (or Vajrayana) Buddhism, the most well-known Buddhist school in the West. Prior to its annexation by communist China, Tibet was a stratified society with rigid social boundaries where the large majority of the population consisted of serfs whose land was owned by a small, often clerical elite. Live dismemberment was practiced as a form of (ostensibly non-lethal) punishment until 1913.
spiritual ideology
Also a rather subjective claim. If you measured spirituality by such metrics as the intensity of one's devotion and willingness to discard worldly vices, the intensity/frequency of religious experience, general personality traits (e.g. sense of tranquility) outside of moments of religious experience, etc., you will find both spiritual and not so spiritual people in all religious traditions. For example, I hardly think you would claim some hard drinking Chinese guy with a Buddha figurine on his shelf is more spiritual than, say, a Benedictine monk.
