In American English, savior is the preferred spelling of the noun referring to (1) a person who rescues another from danger, or (2) Jesus. All other main varieties of English use saviour. When savior or saviour refers to Jesus, the word is usually capitalized in much the same way Christians tend to capitalize God.
The clamor to boost housing as an economic savior is especially odd because we’ve tried this before with dire or fruitless results. [Wall Street Journal]
I believe that Jesus Christ is the Son of God and the Savior of mankind. [quoted on CNN]
I never understood the notion that Mitch Daniels was going to be our savior. [National Review]
Outside the U.S.
With a little love, Nuke has gone from bad behaviour to animal saviour. [Calgary Herald]
But our saviour, the slayer of our enemy in the closing scenes of last week’s great western, is haemorrhaging influence at a critical rate. [Independent]
Technology will have a role, but it cannot be Asia’s saviour alone. [Sydney Morning Herald]