I've often studied this explanation, but have never found out why the Jewish translators of the Septuagint preferred expiation to propitiation:
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The case for translating hilasterion as "expiation" instead of "propitiation" was put forward by C. H. Dodd in 1935 and at first gained wide support. As a result, hilasterion has been translated as "expiation" in the RSV and other modern versions. Dodd argued that in pagan Greek the translation of hilasterion was indeed to propitiate, but that in the Septuagint (the oldest Greek translation of the Hebrew Old Testament) that kapporeth (Hebrew for "atone") is often translated with words that mean "to cleanse or remove" (Dodd, "The Bible and the Greeks", p 93).
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The case for translating hilasterion as "expiation" instead of "propitiation" was put forward by C. H. Dodd in 1935 and at first gained wide support. As a result, hilasterion has been translated as "expiation" in the RSV and other modern versions. Dodd argued that in pagan Greek the translation of hilasterion was indeed to propitiate, but that in the Septuagint (the oldest Greek translation of the Hebrew Old Testament) that kapporeth (Hebrew for "atone") is often translated with words that mean "to cleanse or remove" (Dodd, "The Bible and the Greeks", p 93).
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