If soul i.e. Atma is not affected by fire, water, air, then when a person jumps into water, why should soul leave his body. When suffocated a person, or when a person consumes poison, why should soul leave his body? Do you have answer to this?
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This The Body system which do not co-op with the Water . Soul is an Energy Form which remain in Body till Body Functions Normally .
Life only exists when the Life Supporting environment is there if this Environment is not there , then No life is Possible .In case of Water , Body needs oxygen to survive and when there is no Oxygen(in gaseous form) present in the Pond/lake/river or sea Body can not Function normally .And which resulted in suffocation and then Death . Soul has nothing to do with This Functioning of Body parts .