Father Barry's speech awakens Terry's conscience because it represents some of the same feelings that he had already started to feel.  With Edie calling him a "bum" for his inability to "do more" and his own feelings of moral ambivalence towards his life and participation in activities on the dock, Father Barry's speech is a moral crystallization of what action needs to be taken.  It is for this moment that Terry listens to what Father Barry says and threatens the other longshoremen who want to silence him.  Terry also physically assaults the men who wish to keep Father Barry quiet.  Friendly recognizes the change in Terry, who is more attune to the moral implications of being silent as a result of Father Barry's speech.  The speech itself does not suddenly awaken him, but it enables him to recognize that what he was doing was wrong and had not been done in the right manner.  At the same time, Terry recognizes the moral convergence between what Edie has been criticizing him for and what Father Barry is suggesting he, and the other workers, do.  In this, Terry's moral awakening is assisted by both the conditions that led to it and the speech, itself.