This is simply not true. There are quite a few people who disagree with me whom I consider honest about their disagreement and their arguments. I consider people to be dishonest when they use dishonest tactics.
The major players in any "hot button" issue tend to be dishonest. Someone that parrots the talking points of either side in such a debate is likely to be considered dishonest by me. For example, I oppose abortion; but I think the term "pro-life" is just as dishonest as the term "pro-choice." If I find a roach in my home, I am not going to try to preserve that life. But it is life. But, when there is dishonesty, I am more likely to uncover it in someone who disagrees with me, because I am likely to examine his claims more closely. The sad fact is that few people in the abortion debate really start with their own foundational beliefs and argue their own positions. Most people will repeat the talking points, the rhetoric, and the terminology of the camp with which they most closely identify. Here's a tip. If you do not generally use the word "terminate" but instead use the word "kill" in most situations when it comes up, but onthe topic of abortion consistently say "terminate the pregnancy" I am going to detect the insincerity right away.