"Although the concept of righteousness in our culture has come to refer almost strictly to ethical and moral conduct, this is not the primary referent in the OT. Righteousness does produce ethical and moral conduct, and can be found in such, but the OT concept of righteousness is essentially the "fulfillment of the demands and obligations of a relationship between two persons."3 Under the Mosaic covenant, Israel related to God on the basis of Moses' Law. One's righteousness was judged upon their conformity to this Law, through which they related to YHWH. If they kept the Law, which consisted of many non-moral commands, they were considered righteous (in right relationship) before YHWH. When one broke God's Law, they were in essence betraying the relationship between them and YHWH. This is the essence of sin.4

To demonstrate that the OT concept of righteousness has more to do with relationship than with morality, two examples will be cited. In Genesis 38 we find the story of Judah and Tamar. Tamar was Judah's daughter-in-law. She was married to Judah's eldest son, Er, but he was killed by the Lord (Genesis 38:7). Tamar was then given to the second eldest brother, Onan, to wed. He too was killed by the Lord (38:10). The only son left was Shelah, but he was too young to be given to Tamar in marriage. Judah told Tamar to go to her father's house until Shelah was of age, and promised that at that time Shelah would be given to her in marriage (38:11). When Shelah became of age Judah did not keep his promise to give him to Tamar in marriage, so Tamar devised a scheme to get back at Judah. She dressed herself as a harlot in a nearby city and her ex-father-in-law, not knowing who she was, had sexual relations with her. Since he did not have any payment with him for her services, he gave her his signet ring, staff, and bracelets until he could come back with payment. After Judah left Tamar took off her harlot clothes and left the city. Judah did send back payment, but Tamar (unbeknownst to Judah) had fled. Three months later it was told Judah that Tamar was with child. Judah's fury was full and demanded that she be burnt for playing the harlot. When she arrived she claimed that she knew the father of the child, publicly displaying Judah's ring, bracelets, and staff. Judah, realizing his error, said, "She has been more righteous than I, because I did not give her to Shelah my son" (38:26).

If we were judging righteousness purely on moral grounds, neither Judah nor Tamar could be said to be righteous. When it is understood that righteousness refers to relationship, however, this story makes sense. Tamar's righteousness was not in her act of harlotry, but in the fact that she met the demands and obligations of the relationship between Judah and herself, whereas Judah went back on his word."