In stanza 74, fit III of Sir Gawain and the Green Knight, the lady of the castle offers Sir Gawain a magical green girdle. She explains to him that the wearer of this corset "cannot be killed by any cunning on earth" (Stone, p. 90). Sir Gawain, amidst an ethical dilemma, accepts the gift and chooses to conceal it from the host, Lord Bertilak. This passage contains three of the main themes in the story - the inner and outer conflicts between Sir Gawain's ethics and desire to live, and the test of religion (Howard, p. 152).
When Sir Gawain is offered the girdle, his knightly principles are questioned. The honorable thing would be to reject the offer or to bring it to Lord Bertilak, but Gawain places the preservation of his life ahead of chivalry (Pearsall, p. 78). The knight has withstood the lady's constant barrage of sexual advances, and kept his promise to Lord Bertilak, but when the chance to save his life is presented, he snatches it up without much thought. This point is shown in the line "That never should another know of it, the noble swore outright," (Stone, p. 90) by the way the author puts "Outright" on a line of its own, emphasizing Gawain's quick decision. He is then ecstatic about the thought that the next day he will survive his meeting with the Green Knight. This is described in the line "often thanks gave he/with all his heart and might" (Stone, p. 91).
Later Sir Gawain finds three faults in his actions. The first fault is cowardice, in the main principles of knighthood. The second fault Gawain finds is covetousness, his lust for life. The last fault Gawain finds is his lack of faith in God (Howard, p. 176) . Even when it was shown that God had forgiven him by healing the wound on his neck, Gawain still feels he has sinned and is in turn, unwilling to forgive himself. He decides that more atonement is in order. He then makes the decision to wear the green girdle from then on as a sign of his eternal sin.