Someone told me it should be translated “his seed” referring to Jesus. I seem to remember others saying it was either Eve or Mary. What are the best case or arguments for each position? I am just curious.
Not one single English translation of the Bible agrees with the opinion of “someone”. That, in itself is a strong argument.
Another argument is that it would make no sense to read “his seed” because the passage is contrasting the serpent and the woman. "15 And I will put enmity between thee and the woman, and between thy seed and her Seed;". Then, it continues on describing the action of the woman’s seed (pointing to Christ as that “seed”), "It [her Seed] shall bruise thy head, and thou shalt bruise His heel.” (KJV)
I will put enmity between you and the woman, and between your offspring and hers; They will strike at your head while you strike at their heel.
But by the envy of the devil, death entered the world, and they who are allied with him experience it.
You belong to your father the devil and you willingly carry out your father’s desires. He was a murderer from the beginning and does not stand in truth, because there is no truth in him. When he tells a lie, he speaks in character, because he is a liar and the father of lies.
But the woman was given the two wings of the great eagle, so that she could fly to her place to her place in the desert, where far from the serpent, she was taken care of for a year, two years, and a half year. The serpent, however, spewed a torment of water out of his mouth after the woman to sweep her away with the serpent. But the earth helped the woman and went off to wage war against her offspring those who keep God’s commandments and bear witness to Jesus. It took its position on the sand of the sea.
(Revelation 12 14-18)
Marys offspring will provide salvation for her and everyone in the world. This is the first verse in the bible referring to a savior. The devil is considered the serpent. When we conquer sin with are defeating the devil.
Mary is the woman who the serpent was after and her offspring. This is going on as we speak. The serpent is trying to torment the world and stop Mary from saving us.
(all bible verses from the Revised New American Bible, Fireside Catholic Publishing)