You might want to think about what Emerson is talking about when he writes of "that divine idea which each of us represents." He seems to be talking about the unique, God-given individuality of each person. He clearly believes that relying on and expressing ourselves is an act of prayer and praise to God:
It may be safely trusted as proportionate and of good issues, so it be faithfully imparted, but God will not have his work made manifest by cowards.
Therefore, God wants us to be ourselves and express our individuality, but according to Emerson, the best place for us to be able to do this is in Nature rather than society. Being in Nature allows us to understand our God-given calling:
And we are now men, and must accept in the highest mind the same transcendent destiny; and not minors and invalids ina protects corner, not cowards fleeing before a revolution, but guides, redeemers, and benefactors, obeying the Almighty effort, and advancing on Chaos and the Dark...
However, when we move into "the world" or society these voices become "faint and inaudible" as we are forced to consider suppressing our individuality for the needs of the many.
Therefore, "Self-Reliance" throughout expresses Emerson's firm belief that we need to be non-conformist and self-reliant as part of expressing our God-given individuality. He argues that the best arena for us to do this is in Nature and away from "society" that he sets in opposition with non-conformity.