Your claim that the Rainbow Serpent is analogous to Satan is wrong. Completely, totally and utterly wrong. Please stop trying to claim otherwise.
"The Rainbow Serpent or Rainbow Snake is a common deity (also known as Wagyl, Wuagyl, etc.) often seen as a creator god and a common motif in the art and religion of Aboriginal Australia... It is viewed as a giver of life, through its association with water, but can be a destructive force if angry.
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It is known both as a benevolent protector of its people (the groups from the country around) and as a malevolent punisher of law breakers. The Rainbow Serpent's mythology is closely linked to land, water, life, social relationships, and fertility. The Rainbow Serpent often takes part in transitions from adolescence to adulthood for young men and swallows them to vomit them up later.
The most common motif in Rainbow Serpent stories is the Serpent as creator, with the Serpent often bringing life to an empty space."
Rainbow Serpent - Wikipedia
Does Satan fulfill a similar role in Christianity? No. Just accept that you are wrong about this, okay?