Arthur McGill on sin:

. . . There is another element in Paul’s contrast [he is discussing Romans 6–8]. What does he mean by sin? Or better, what does Paul mean by an identity-in-sin? Identity-in-sin means not to live from God, not to honor God as the constant source of our being, not to be thankful to God as the one who constantly gives us ourselves. Identity is sin when persons imagine that their being has been conferred over to them, when they try to live out of themselves in terms of the reality which God may have once conferred onto them but which they now hold in their own possession. Sin is to refuse to live out of the reality which a person constantly receives from God. It is the pride, the self-glory, which Paul sees as sinful identity. (Arthur McGill, “Death and Life,” 52)

Excellent! This reminds me of Yahweh’s prediction of Israel’s coming rebellion:

. . . When I have brought them into the land flowing with milk and honey, the land I promised on oath to their forefathers, and when they eat their fill and thrive, they will turn to other gods and worship them, rejecting me and breaking my covenant. ~Deuteronomy 31:20

Instead of remembering the source of their life, they begin to think that their blessing is of their own making, of their own gods (themselves), of their own possession. Instead of remembering that all that they have, and continue to have, is dependent on its ultimate source, Yahweh. Instead of living ekstatically (think of Jesus’ kenosis, Phil. 2:5-8), remembering that their life is one of looking out (i.e. to the Lord), life as sin is one of looking in . . . and worshiping things as if they were of their/our own making (this is not the way of the cruciform life or God).