From the Westminster Shorter Catechism:
Q. 14. What is sin? A. Sin is any want of conformity unto, or transgression of, the law of God.

From the Baltimore Catechism:
Q. 278. What is actual sin? A. Actual sin is any willful thought, word, deed, or omission contrary to the law of God.

From Senator Obama:
Q. Do you believe in sin? OBAMA: Yes. Q. What is sin? OBAMA: Being out of alignment with my values.

Not that there is anything to the chatter about Senator Obama’s “Messiah complex,” mind you.