Here's the best I was able to find:
** SPOILERS **
The Prologue, a masterful sequence lovely b&w slow motion, shows a couple, He and She, making love while their innocent baby becomes fascinated by the sight of snow falling outside an open window, climbs up on the sill, and falls to his death. This is Man's Fall from Grace. Consequently, She (Charlotte Gainsbourg) falls into guilt and depression so deep she is hospitalized. That is one half of Original Sin. The character named He (Willem Dafoe) insists she cut off her medication. He will cure her himself. That is the other half. Her sin is Despair. His is Pride. These are the two greatest sins against God.
At the end He stands atop a hill while a legion of unnatural humans ascends toward him, evoking "Night of the Living Dead." The suggestion is Biblical, but not from the Bible we know. The human figures are not naked, climbing toward birth, but clothed, climbing toward death. After their fall in the Garden of Eden, Adam and Eve learned shame, and covered their nakedness. In this evil world, they are created covered, and by their sins are cast out into nakedness.
Von Trier's original intention, it's said, was to reveal at the end that the world was created by Satan, not God: That evil, not goodness, reigns ascendant. His finished film reflects the same idea, but not as explicitly. The title "Antichrist" is the key. This is a mirror world. It is a sin to lose Knowledge rather than to eat of its fruit and gain it. She and He are behaving with such cruelty toward each other not as actual people, but as creatures inhabiting a moral mirror world. As much as they might comfort and love each other in our world after losing a child, so to the same degree in the mirror world they inflame each other's pain and act out hatred. This would be the world created by Satan.
Just as a good world could not contain too much beauty and charity, an evil world could not have too much cruelty and hatred. He is making a moral statement. I'm not sure if he's telling us how things are, or warning us of what could come.