Satan: You read that overblown press kit they call the Bible. You know what you're going to find out? Shit happens.
Satan: Sometimes, Hell comes to you.
Cardinal: We're not afraid to die for our cause.
Jericho Cane: Good, because I'm not afraid to kill you.
Father Kovak: You think you've seen everything? There's a whole world you've never dreamed of. Thomas saw it, and it destroyed him.
Jericho Cane: I've seen a lot, but nothing would ever make me cut out my tongue.
Father Kovak: Wait a few days.
Satan: How do you expect to defeat me when you are but a man, and I am forever?
Bobby Chicago: You'd be amazed what you'll agree to when you're on fire.
Bobby Chicago: You know, sometimes you border on competent.
Jericho Cane: I know, it's scary isn't it?
Bobby Chicago: Is this considered interfering with a police investigation?
Jericho Cane: Hey... we're private citizens having a conversation with another citizen. I mean, I don't think they found a way to outlaw that... at least not yet.
The Man: Something good happens, "It's His will." Something bad happens, "He moves in mysterious ways."
Chosen answer: Satan had to protect the host's body from harm by the Catholic priests who might try to stop him with holy "weapons." At the end, when Jericho impales himself on Michael's sword, Satan is cast out of Jericho's body because of the holy power of the sword.
Bishop73
There's no proof holy weapons could hurt him one way or another. He certainly wasn't fazed by crosses. I find hiring security more of a plothole. Arnold impaled himself on the sword so that his body would be pinned and Satan couldn't use him. Satan was driven out because his time on Earth was up. He failed to conceive. You can see the prison of Hell engulfing him. The sword didn't matter. The time did.