Why are so many christians, at least the ones who advertise the fact, so dishonest?

     It is my experience that people who call themselves christians and draw attention to it, even when they are not asked, are dishonest. Now, I can't say that all such people are dishonest. There may be some honest ones that I just haven't run across. But, in my experience, they are dishonest. They will lie about what non-believers say and then ask why the non-believer is too prideful to admit he wrong about something he didn't even say. It has been said that you shouldn't judge a faith based on the actions of the supposedly faithful. And it is certainly true that "bad apples" are far more conspicuous. But I would like to know why these people act the way they do.
     I seek understanding. Tell me in your own words. What motivates you? Do you think you are serving a higher cause with dishonesty? If so, what is it? Do you think that you are forced to be dishonest? If so, how? I really want to know.

UPDATE:

     I will not challenge any reasoning you give, as your reasons are, of course, your own. However, if you make the claim that your actions are not dishonest, I may challenge that, especially if I think I have evidence that you are dishonest.