How to "preach our unique remnant message" while staying alert to the challenge that we too can fall into the "heinous sins described in Rev 13"? 

The first situation sounds like confidence and an assurance of being right, while the second is all about recognising the insidious ways we can become the monster we claim to fight. Probably each individual christian feels more at home in one or the other of these extremes, and there are plenty of positions in between. It is humbling to recall the experience of David accusing himself after a story from the prophet Nathan.