Was Abraham justified by faith or works?

Was Abraham justified by faith or works?
He was justified by faith.	He was justified by works.
Romans 4:2 For if Abraham were justified by works, he hath whereof to glory.	James 2:21 Was not Abraham our father justified by works, when he had offered Isaac his son upon the altar?

Ebon Musings: Some Biblical Contradictions on the Issue of Faith vs. Works
Christian responses: CARM; LookingUntoJesus.net; Rational Christianity; New-Life.net; ChristianAnswers.net; SAB: A Response; Tektonics