I agree fairly completely with all that you just said, Paeter.
As for the difference between real vs fictional - I'm concerned with emulation - the tendency of people to adopt the beliefs, attitudes, and actions of their heroes; fiction contributes to this by shaping the way we think about a given subject. If anyone is in doubt about the extremes to which this may be taken, I offer up the fact that "Jedi" is now considered a valid religious choice in both the US and the UK.
Fictional models of magic shape the way we perceive and apply theology and philosophy. In the case of Spirit Blade, "Spiritual Gifts" are specific in source and "miraclai" is morally neutral in its capability. This leads the consumer to consider the source of their own abilities, the obligations that those abilities entail, and the moral consequences of actions.
Gandalf's abilities are divinely appointed, as are those of his fellows Radagast, Palandro, Saruman, and Sauron. The wizards are a class of people with designated abilities and responsibilities. They hold positions of authority, and wield power to match. Magic is a function of spiritual authority; mortals attempting to use magic do so as an effort to usurp the authority of another. This is rebellion in the classic sense, and leads the reader consider their place in the natural order, and their own duties therein.
Harry Potter's abilities are purely natural in origin. Their consistent execution is tied to repeatable formulae. This is the definition of science. Harry's magic is textbook superhero - powers and abilities far beyond those of mortal man. Spiritual authority is non-existent, and no spiritual implications accompany his action. In fact, the morality of Harry's power is wholly defined by his actions and choices. The reader is led to consider that morality is tied to human will, right and wrong are measured in degrees, but individual choice is the ultimate arbiter.
Harry Dresden lives in a world where he deals routinely with spirits and assorted supernatural phenomenon. Magic is the function of human will imposed over a reality that itself is subjective in its manifestation. In such a case, Harry is a moral, good person not because he acts to protect other people, but because he is successful when doing so. The creatures he acts against are no less moral in their endeavors - they simply have different goals.
Which of these is witchcraft?
Which of these models is sinful in its application of thought?
It may be positive to play at being Gandalf. Desiring to be a wizard like Harry Potter in a world of wonder surely is harmless at least. But Harry Dresden? When my protagonist elicits such sympathy that his crimes are forgiven because his intentions are good, surely that is detrimental.
At the end of the day, I can't be Gandalf. His power comes from Divine appointment. I can't be Harry Potter; his power is inborn, a result of living in a world where reality is slightly different. But I can be Harry Dresden. I may never encounter a spirit or corner a monster, but I have a fairly obstinate will and the ability to impose that will on others. If my intentions are good, and the results successful (or at least non-detrimental), then isn't any action I take justified in that pursuit? From this perspective, there exists no moral difference between making a speech, pointing a gun, or casting a hex.
This same issue may be applied to any text that expounds a method of thinking, be it fiction or treatise. The great advantage in dealing with fantasy is ability to make the abstract concrete. The great disadvantage is that people have been trained to react to certain words emotionally rather than logically: words like witchcraft, magic, slavery, or free will.
As Paeter said, the principles of Scripture need to be applied to the source material in order to extract an accurate method of thinking from a fantastic representation. Given that the human mind WILL act on the intellectual material it consumes, I believe its important to understand how our fiction is training us to think.
Given that I am probably prone to thinking about my entertainment WAY too much ... am I the only one who thinks this way about these fantasies?