QUOTE
In both Christianity and Islam, the inequalities among creation - all that you describe - are just the absolute discretion of God, the creator and man cannot question, complain or even try ti find out the reasons therefor — a position similar to what was laid down for the sudras according to the Dharmasastras. Hence, those religions don't need to explain these inequalities; may be we can take them as sudra religions.
UNQUOTE
I wish to explain Sudra and quote my Internet Guru below :
sudra is not the person. it is varna. a person displaying sudra characteristic may becalled sudra for that time. likewise, brahmana is one who displays characteristic of brahmana varna, which depends on his karma samskara determined gunas. it is not permanent.
Varna applies to all people who are dharmik, conscious of what is correct. Those who identify with physical body and acts with selfish motives are avarna, mleccha,untouchables.
Take the case of Ratnakara. he too was a mleccha, robber in jungle, avarna. Later he developed dharmik consciousness and became Maharshi Valmiki, a brahma jnani, a brahmana.
Varna is not something people are branded with when they are send out from the otherworld. It is the expressed behavior of a person here that determines varna.
Varna is not something mandatory or enforced. It is, expressed behavior of a person, which again, changes with time, that determine varna.
sudra is one who is motivated by the purushartha of kama. when u r motivated by kama, u r sudra too.
when u act motivated by desire to uphold dharma, u r kshatriya.if motivated by materials, their working, production, u r vyshya. when u act motivated by desire to know urself, know the basis of all that is seen, experienced, u r brahmana.
when not motivated by the above/when action motivated by selfishness/negative reasons, the person is avarna. mleccha.
actions form habit, which shapes character, which defines life. people, thru continuous actions motivated by predominant varna in them come to exemplify the varna. However, it is not transmitted to progeny. children develop their own character, though influenced by parent/environment. It is not community that decides varna. Rather, varna is the basis for company, and community.
a person in pursuit of realization of brahma sees through the temporality of external appearances and is not distracted by kama or artha or even dharma. a person passionate about dharmikata or righteousness, likewise sees through the impermanence of external appearances and is not swayed by kama or artha. A person engaged by materials is dealing with more concrete thing than mental imagination. A person swayed by kama is enamoured by appearance. The last mentioned state is not conducive to receiving jnana and so sudra is not given veda jnana. The same sudra or even mleccha, if develops dharmikata, like Ratnakara did, can acquire brahma jnana.
varna changes with behavior. it depends on variation in gunas. which again depends on karma samskara. Pattern of behavior that emerges, through repeated pursuits of a particular kind determine the predominant varna of a person. It can be reinforced or changed. nishkama karma exhaust karma samskara and raise the dominant motivation of the person from kama to artha, then to dharma and finally, moksha.
practices or customs have little to do with varna. a chandala was recognised as brahma jnani by Adi Shankaracharya