Maybe Satan was over-thinking it a bit
So I get the story line that Satan needed his son to get into politics in order to usher in the apocalypse... but why not skip all the events in the first 99% of this move and just have him be born to the president of the united states in the first place?
Was it just "timing" that the anti-christ HAD to be born on June 6, 2006 and the Thorn family was the only way to make it work? I never knew Satan was so sentimental about that kind of stuff, so I guess I learned something in this movie: Satan has a lust for power and evil that can never be quenched, but he will wait thousands and thousands of years just to make a symbolic point.