Throw in the lead singer of Bush as bad angel Balthazar, a psychic priest who hears the voices of the dead when he puts his hands on newspapers, a small ferrety man with glasses who lives in a bowling alley and spends his time collecting artefacts such as a dragon's breath flame-thrower, Rachel Weisz as a cop who always seems to know when to point her gun at a bad guy and is trying to get her dead sister's soul released from hell, Lucifer popping up in a nice white suit and .... well, I don't know what you get.
Complete hokum, but oddly enjoyable and with some killer dialogue. My new favourite film quote, the Angel Gabriel to Constantine:
'You're dying because you've smoked thirty cigarettes a day since you were fifteen. You're going to hell because you took a life. You're fucked.'