In the first chapter of the Gospel of Mark, we encounter Jesus healing and casting out demons. More than once the demons seem to know exactly who Jesus is: "We know who you are - the Holy One of G-d! You have come to destroy us!".
Jesus does not allow the demons to speak, even though, on one level they might speak the truth. This always stuck me as odd until I was led to the conclusion that Christ does not allow demons to speak because He will not allow himself to be defined by Evil. A similar principal was at play when Jesus was tempted by Satan in the wilderness: He would not allow Evil to dictate His actions.
So I believe it must be for us as well. The difficult part is that while we must not let the evils of this world define us negatively, we must also allow ourselves to be defined positively by the evils of the world. It is in fact only G-d who places the length and breadth and width on our lives; only G-d who really defines what we are to be: namely a new creation in Christ... for if anyone is in Christ (s)he is a new creation... (2 Corinthians 5:17)
Johannus Rembrandt 4900 4 M/P Digital Organ, Third-Westminster Presbyterian Church of Elizabeth, NJ