Nasty and untrue
Well, who wants to be a nasty person? Certainty not I. So what's the alternative? Live in doubt with a touch of agnosticism. That seems rather harsh, but have you really listened to the rhetoric of the emergent movement? They say that deconstructing orthodox (truth) belief and marrying it with a correct orthopraxy (practices) we can have a true orthodoxy where we can question everything, and are sure about nothing. This is suppose to be good.
The problem is that what is true is not dependent on our behavior. It is not even dependent on our own right beliefs. We can be wrong about something, but that doesn't mean we are wrong about everything. For instance, let's say we get directions to a church from one of its members. We may find out that the directions were wrong, but the meeting times were correct. We may even look up the directions on a map, and eventually find our way to the church. So it doesn't follow that because that member was wrong about the directions, that she is wrong about everything pertaining to her church (i.e. the schedules). It also doesn't mean that I cannot know the truth about the directions either—I consulted a map.
Raise your hand if you're sure
But doesn't surety cause division? Yes and no. When the apostles were sure about something, it often caused schisms with those who disagreed. The issue is not the division, the issue is who is right. Ultimately, Satan holds a point of view. Does this mean that God is wrong because He doesn't respect that, and tells us not to respect that? Obviously not, because God is the end of the matter and the ultimate cause of the matter (Beginning and End).
Remember, Satan likes to masquerade as an angel of light or as a wolf in sheep's clothing. In other words, he masks himself to infiltrate our ranks with error. And this error is disguised as truth. If Jesus is the embodiment of truth, then we better listen to him, to his apostles, and to those prophets he sent (Matthew 7:13-27; Ephesians 2:19-20), and stop paying so much attention to the teachings of men. And at worst, the teaching of hypocritical liars. (1 Timothy 4)