Far too often, we find ourselves in a compromised and completely lost secular point of view. We step out in faith and then get swept away by the interests that surround us until we lament what has become of the faith that we once had. I know Calvin would suggest that we were never really truly saved if the world can sway us so easily. In turn I would retort that the Devil is in the details and the downfalls. He knows how to distract and lead the sheep away.
I wonder if David is speaking of peace in his heart and his life, because I know I would be. He was lost to the warmongering and thus lost the peace that God held over his life.
http://bible.com/59/PSA120.6 Too long have I had my dwelling among those who hate peace. I am for peace, but when I speak, they are for war!