Do you still believe in God, and that the Bible is His word?
Yes and yes.
aren't you being unreasonable by your refusing to allow Revelation 13 to weigh in on the matter being discussed here?
No, I don't think so. Revelation 13 is a symbolic prophecy that can (and has!) been interpreted in any number of different ways. The common interpretation among Christians is that the "beast" is representative of a world leader (or perhaps a world power) that will dominate immediately prior to the return of Christ. Others have applied the meaning to a religious power, such as the papacy. The only group I know of that interprets the beast as meaning all human governments is Jehovah's Witnesses. One reason that their interpretation is not more widely accepted is likely that it flies in the face of so many other scriptures which demonstrate that human authority comes from God, not Satan - Romans 13 being a prime example of that.
Your statements imply that you aren't so sure yourself about the meaning of Revelation 13, yet you express certainty when it comes to Romans 13.
And with good reason. As I said, Revelation 13 is a prophecy of future events, couched in symbolism. It is subject to all kinds of different interpretations that can be advanced within the language contained in the chapter. Romans 13, however, is a straightforward exposition of doctrine. There's nothing difficult to understand in it. That's why I said we ought to be interpreting Revelation 13 in the light of Romans 13, and not the other way around. And such an interpretation would rule out the understanding that the "beast" could be all political governments, since one thing we know about the beast is that it receives its power from Satan, and what we know about earthly governments from Romans 13 is that they receive their authority from God. Altering the clear intent of the plain words at Romans 13 to allow for a highly speculative interpretation of Revelation 13 is nothing more than twisting the scripture - something Jehovah's Witnesses are very good at.
I've already shown that Romans 13, by itself, can easily be understood to mean something other than what you think it does ...
No, I don't believe that you have. What you did say was:
The fact that the text at Romans 13 states that "there is no authority except by God" explains how it can be said that the authorities stand "placed" in their positions by God. In other words, were it not for God's allowing such governments the power that they possess they wouldn't exist.
But you are the one who is inserting the concept of allowing into the text. There is nothing in the context of Romans 13 that carries the idea of allowing. To say that "there is no authority except by God" does not imply that he allows authority, but that He establishes it. That this is true is further confirmed by the statement that these powers are placed in their positions by God. After the above assertions, you went right back to your interpretation of Revelation 13 for further support.
I'm glad we are having this discussion, because I had never pieced together in my mind before the fact that Romans 13 (and other texts, like Daniel 4) actually refute the Watchtower's interpretation of Revelation 13 - clearly, the same powers cannot receive their authority both from God and from Satan. Since we must interpret vague and symbolic statements in light of plainer ones (and that is a commonly accepted rule of Biblical interpretation), Romans 13 would have to rule in the sense of actually meaning what it says - governments of men receive their authority from God. Therefore, these same governments could not possibly also comprise the "beast," which is explicitly said to receive its authority from Satan.