Some of these pictures and descriptions may give away plot details that you might not want to know before watching the film.
This is an Arnold Schwartzenneger action movie, so you know exactly what you're going to get - lots of butt-kicking, explosions, absurd cliff-hangers, people on fire, and other mayhem, along with lots of unintentional comedy and witty one-liners, capped off by Arnold saving the world at the end. They typical action movie format. Arnold is (no surprise) an ex-cop whose wife and daughter were killed, making him feel guilty and driven to drink booze along with breakfast smoothies made with coffee, Chinese take-out, and old pizza he finds on the floor. Actually Arnold's acting is not bad here. His race-against-the-clock mission is to stop Satan from having sex. We see lots of Priests and Cardinals and even the Pope, all fighting the prophesized battle against the devil and end of the world, but with different strategies, including a tongue-less hit man priest and a secret Devil-fighting Papal army.
Satan takes over the body of Gabriel Byrne when he comes to New York City on the eve of Y2K to find and impregnate a young woman who was chosen to be the mother of his child when she was born twenty years earlier (Robin Tunney). Somehow if Satan has sex with her an hour before midnight, the world will end, but how that will happen isn't made very clear. Do we have to wait until she has his baby or is the act enough or what? Satan here has a lot of powers - he can punch someone right through the head and he can light his urine on fire to blow up a city block, but otherwise he chases the girl slowly and incompetently and relies on incompetant humans to help him. None of that matters, really, because we're here to watch Arnold jump in and out of a helicopter, to watch Satan stab a priest in the head with a dagger in the shape of a cross, and to watch Arnold run over Satan with a subway train, shoot him with a rocket, blast him with a machine gun, and throw him out a 20th story window. We also get to see a disgusting Satanic ritual with a rattlesnake.
Minutes after Robin Tunney is born, a hospital nurse takes her to the basement where a bunch of devil-worshippers are waiting. (There are lots of fans of Satan in this New York, just as there were in Rosemary's Baby.) The leader pulls a rattlesnake out of a jar by the neck (which is pretty gutsy) sticks a knife in it, then pokes his finger into the wound to cover it with the snake's blood. He tosses the bloody carcas back into the jar, then sticks his bloody finger in the baby's mouth so that will be the first thing it eats.
We see a real live Western Diamond-backed Rattlesnake in the jar, grabbed and held up by the neck, but the snake he stabs and bleeds is a prosthetic snake. The American Humane Association disclaimer at the end says that no animal was harmed in the making of the movie and that prosthetic animals were used.