Jdubla:
If you sincerely question how someone who doesn't believe in the Bible as God's word can refer to what it says, I will try to answer that question.
Let's assume that there is a book you don't believe is God's word, but other people do. Let's take the Book of Mormon for example. Let's say that it relates that God or Christ did certain things that you personally find repulsive and not fitting in with the character you attribute to them. If someone then asked you why you didn't believe the Book of Mormon was God's word, could you cite these passages as your reason without appearing "ridiculous"? I think so. In fact, I think the only way you could appear ridiculous in such a situation would be to say, "Oh, I can't tell you why I don't believe because that would involve citing parts of the book, and I can't do that because I don't believe in it."
Now let's look at the God of the Bible. I think your question is: If I don't believe such a being exists, how can I say that he did this or that? Well, obviously I don't believe he did this or that since I don't believe he exists. What I am doing is assuming the argument of the other side. This is a common way of discussing things (as is "playing devil's advocate" when you argue for the opposite point of view to find holes in your own point of view). Perhaps another analogy would help explain this:
Let's say that you don't believe in Zeus. When I ask you why, you say, "Well, for one reason he turned into a swan and raped Leda. I don't think that's an action a God would take." But then I reply: "That's not a valid argument, since you don't believe Zeus exists you can't cite any actions of his; a non-existent being can't perform any actions." I would be half right, but I'd be missing the point. The point isn't that you actually believe Zeus did this or that, the point is you don't believe in Zeus because those who do believe in him contend that he did this.
If the Bible says that Jesus called people "vipers," "fools," and "dogs," it little matters whether I personally believe in God, the Easter Bunny, or Humpty Dumpty; the Bible will still say what it says. The Bible is what most Christians (and certainly the Jehovah's Witnesses, whom this forum is supposed to be geared towards) use as the source of what Jesus did and said. Therefore it seems logical and appropriate to refer to it in this context. I just cannot see how it could be considered ridiculous. A discussion about what Jesus said WITHOUT referring to the Bible -- now THAT might be ridiculous.