[JenB]

Oh, was the ugly baby-thing supposed to be the Antichrist? I was just weirded out by that.

Gibson made a very good choice with his portrayal of Satan.

[RosieCotton]

That's the way a lot of people are interpreting it.

Apparently that wasn't specifically what Mel Gibson had in mind, though. From an interview:

But what about the ugly baby? "Again," said Gibson, "it's evil distorting what's good. What is more tender and beautiful than a mother and a child? So the Devil takes that and distorts it just a little bit. Instead of a normal mother and child you have an androgynous figure holding a 40-year-old 'baby' with hair on his back. It is weird, it is shocking, it's almost too much-just like turning Jesus over to continue scourging him on his chest is shocking and almost too much, which is the exact moment when this appearance of the Devil and the baby takes place."

[Scott from the Left Coast]

Yes, obviously that was the child of Satan -- the AntiChrist -- the one that was to come as the opposite of the Christ. It was interposed with shots of Christ suffering and his mother watching, while the androgyenous Satan was coddling (almost looked like suckling) his own warped offspring in his arms.