I feel like he may not be THE antichrist, but rather the only one who can truly bring him forward.

It's the only reason I can come up with that explains the "no copulation! But let's put you 2 feet away from each other with no other precautions just in case" mentality about the kids, too. Keep them close enough to be tempted but pure enough for whatever "ritual" is coming next upon Michael's arrival, I guess. I don't know. Cause like if in satanism everything biblical is reversed and Saint Michael historically being the Angel of Death, could our evil Michael have power over giving life? Especially with that being one of the 7 wonders and the hinted at witchcraft with Michael involved...