How can you be held to a requirement that didn’t exist until several hundred years after you died? That would be the case with many of the children of Israel.
If God determined that the OT figures needed any sort of purging of original sin to be let into Heaven, God would have taken care of that himself just before they entered Heaven, since obviously they had no opportunity to be baptized on earth since Jesus had not yet instituted that sacrament or told them of the requirement.
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