Also, IF there are various books of the Bible that speak of the end times (both OT and NT), and IF you believe that the entire Bible is inspired, then I don't see that it is a doctrinal theory to take the parts of all books that speak of the end times and put together a comprehensive picture of what they are saying what would happen during the end times.
You have to explain why you are connecting books that do not directly reference each other. Revelation does directly reference by name the Serpent, Egypt and Sodom from the Torah and therefore you can connect those books to Revelation within reason. The harlot is mentioned in Isaiah so you can include that book too. However connecting any of the 4 Gospels requires some sort of proof that such an action is merrited. Using the alleged inspiration of the Bible cannon is not sufficient because you then have to give credence to ALL catholic traditions and doctrine because they were the ones that closed the Bible cannon. Surely you don't want to do that. A better approach is to ONLY use texts that directly reference each other, imo. The writings of "Paul" and "John" don't seem to be aware of the four Gospels located in the Bible Cannon.
Take John's reverence to the anti-christ for instance:
3 but every spirit that does not acknowledge Jesus is not from God. This is the spirit of the antichrist, which you have heard is coming and even now is already in the world.
People have always questioned the authenticity of the epic of Jesus and his death and today is no different. Most people did not see anything and therefore had to be convinced by some means. No where in John or Paul's writings do you see reference to the miracles performed by the Jesus of the Gospels. Paul's Jesus is different than the Gospel Jesus which is fishy. You would think that John and company would identify Christian's who acknowledged not only Jesus existence, but also the miracles that he performed that no one else could. Convincing people in that day to follow Christ would have been difficult and all methods would have been used. Did anyone else walk on water? Did anyone else turn water into wine? Despite this content what they taught was simply to "acknowledge" Jesus which would mean that you believed he came and died and was the Son of God. So anyone, or any spirit, who DOESN'T acknowledge what Jesus came and did is not from God and anyone NOT from God is part of an "antichrist" class. This is not an organized group of people with a named leader, but merely an overtly rational way of thinking. "I didn't see it therefore it didn't happen" type of thing.
-Sab