Hell wants him. Heaven won't take him. Earth needs him... The wager between heaven and hell is on Earth. John Constantine (Keanu) is a world-travelling, mage-like misfit who investigates supernatural mysteries and the like, walking a thin line between evil and good. Constantine then teams up with a female police detective, Angela(Weisz), who seeks Constantine's help while investigating the suicide-like death of her twin sister...
Based on the DC/Vertigo comic book Hellblazer and written by Kevin Brodbin, Mark Bomback and Frank Capello, Constantine tells the story of irreverent supernatural detective John Constantine (Keanu Reeves), who has literally been to hell and back. When Constantine teams up with skeptical policewoman Angela Dodson (Rachel Weisz) to solve the mysterious suicide of her twin sister (also played by Weisz), their investigation takes them through the world of demons and angels that exists just beneath the landscape of contemporary Los Angeles. Caught in a catastrophic series of otherworldy events, the two become inextricably involved and seek to find their own peace at whatever cost.
andrejtu
Answer: Sin for a good reason is still sin, and as Gabriel says earlier, you can't buy your way into Heaven. Real Catholic dogma, however, doesn't hold the mentally ill as condemned for committing suicide.
Greg Dwyer
Except Isabel wasn't mentally ill. She saw angels and demons just like Constantine did. It was her parents who believed she was mentally ill.
While suicide is a mortal sin, it's shown later (as in major plot point) that sacrificing yourself to save the world is a redeeming act.
Yes, but Constantine also said "My parents were normal. They did what most parents would do. They made it worse. You think you're crazy long enough, you find a way out" which could relate to Isabel losing her sanity in a way as well because of her family and how they saw her. The whole Isabel's sacrifice is added by the novelization but the movie is ambiguous about the suicide.
mp1920
Except Isabel wasn't mentally ill. She saw half breeds just like John did.
Sacrificing yourself for others isn't a sin.