miscreant

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun One who behaves badly, often by breaking rules of conduct or the law.
• noun Archaic One who does not believe in a certain religion; an infidel or heretic.

from The Century Dictionary.

• Misbelieving; unbelieving; infidel.
• Vile; detestable.
• noun An unbeliever; a misbeliever.
• noun A vile wretch; a scoundrel; a detestable villain.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Holding a false religious faith.
• adjective Destitute of conscience; unscrupulous; villainous; base; depraved.
• noun obsolete One who holds a false religious faith; a misbeliever.
• noun One not restrained by Christian principles; an unscrupulous villain; a depraved person; a vile wretch.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Lacking in conscience or moral principles; unscrupulous.
• adjective theology Holding an incorrect religious belief.
• noun One who has behaved badly, or illegally.
• noun One not restrained by moral principles; an unscrupulous villain.
• noun theology One who holds an incorrect religious belief; an unbeliever.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a person without moral scruples