Science is a technique for doing two things: it allows us to understand the world around us, and it allows us to detect and correct any misunderstanding that may arise in the process. Both aspects of science stem from the same practice: making detailed and verifiable observations of the reality that surrounds us. This practice of constantly referring back to the real world is what makes scientific understanding so useful and reliable.
Obviously, in order to make detailed and verifiable observations of something, it first has to exist in the real world. Since the Gospel Hypothesis implies that God really does exist, and since the Myth Hypothesis implies that He does not, the science of theology is clearly going to have very different characters depending on which hypothesis is most nearly correct.
The Gospel Hypothesis presents us with a God who not only exists in the real world, but who is also perfectly loving, perfectly good, perfectly wise, and perfectly powerful. Since we are the people who are the object of His perfect love, and since He wants very badly for us to experience eternal, personal, harmonious fellowship with Him for all eternity, this implies that we are going to have ample opportunities to observe Him, as He interacts with us, in the real world, in person, both to give us the guidance and nurture we so desperately need, and also because He just loves to hang out with us.
Theology, thus, ought to be like any other observation-based science, such as astronomy, or zoology, or even sociology. It ought to present us with an objective, real-world phenomenon we can study, and as time goes by, later scientists ought to be able to build on the foundations laid by earlier observers, refining and testing their observations (much to God’s self-revelatory delight). There may be different schools of thought at times, but as with all observation-based sciences, continued observations are going to reinforce correct understandings, and discourage erroneous ones. Theology, therefore, will develop like other sciences, with initially divergent hypotheses converging over time to a common, reality-based understanding.
Meanwhile, if the Myth Hypothesis is true, we’re going to find theology assuming a very different character. According to the Myth Hypothesis, no such god actually exists, so observation-based science is out. Instead, theologians are going to have to base their studies on each other as much as on the initial superstitions, exaggerations, and outright fantasies that made up the original stories. Progress is going to be made on the basis of charisma and consensus, rather than by observation and verification, or alternately, too-rigorous application of scientific principles will lead to increasing liberalism and skepticism, even in seminaries and religious institutions.
Where observation-based scientists can make their mark on science by achieving new insights that harmonize a large body of verifiable observations, theologians will have to make their marks along more political lines, achieving pre-eminence not by how much data they explain but by how many people they persuade. There are many unsung and unremarkable theologians who only repeat the ideas of their predecessors, and thus fade into obscurity. Standing out from the crowd requires innovation, iconoclasm, the introduction of a remarkable theology, not to mention a certain skill at marketing and politics. To contribute to the advance of theology requires making changes to theology, and in the absence of a real-world God, those changes are most likely to be made by people whose real talents are political and rhetorical, rather than scientific.
Compounding this tendency will be the normal evolution of cultural values and priorities. At certain times, societies will be ripe for new theological ideas more attuned to the times. Perversely, however, religion will derive its authority from dogmatism and tradition, which will reinforce the status quo against the upstarts. Society will be divided, progressives and conservatives will each find reasons to support the theology most in harmony with their outlook and agenda. This in turn will tend to move the field, over time, in the direction of division and sectarianism, rather than converging on a common, underlying, objective reality the way observation-based sciences do.
So what do we see in the real world? Do we see theologians converging over time on a common understanding of God? Do we see seminaries and other institutions of higher education becoming more and more devout theists as time goes by? Or do we see institution after institution fall into increasingly skeptical liberalism the longer they study their subject? Do we see believers dividing over time into more and more splintered groupings, until many believers proudly declare themselves to be non-denominational, meaning their theology is independent from everyone else’s?
It’s pretty clear that the real world of theology looks exactly the way you’d expect it to look given the truth of the Myth Hypothesis. God’s absence from the real world makes it impossible for theology to be an observation-based science, and so the theologians are left to try and capitalize on each other’s speculations and rationalizations and superstitions, in the absence of any real-world standard against which you could test the competing theories. You can measure the popularity of the various theologies, as they compete with one another to attract the greatest number of followers. And yet, even though theologians themselves can clearly see the fallacy of using popularity as the ultimate standard of correctness, they have no better standard to propose. God is not here, He does not make Himself available for observation in the real world, and theologians are reduced to being public relations agents for their own opinions. And thus theology fractures and splinters along the lines of human superstition, gullibility, and pride.