I am surprised that you didn't have at least one class on World Religions at the seminary.
It seems to me that as a future pastor you should have been encouraged not only to study theology but also to study humanity, the better to minister to your flock. Ancient myths can offer many insights into how the human mind works, and how people down through the ages have viewed their relationship to the divine powers that shape their lives. And many of these beliefs still hang on. The popular conception of God expressing his displeasure with thunder and lightning bolts -- is that really based on the Bible (where God seems to have a heck of a lot of ways of expressing his wrath), or are we seeing echoes of the old pagan gods like Thor and Zeus?
There was no class on World Religions even offered at seminary. I did take a course on Islam, broad survey stuff but with a teacher who had been a missionary in a country whose major religion was Islam for decades before teaching. Asking him questions was like tapping into an artesian well.
I would say that my seminary saw a greater need for a depth of understanding about the Christian religion, than the need for an understanding on a world wide basis. Given the stated purpose of my serminary was to prepare preachers for North American churches, this is not an illogical direction.
And fantasy, the best fantasy anyway, is not merely about make-believe. It's about inner realities: our dreams and impulses, and the things that the heart knows but the rational mind is incapable of expressing directly. It is the same with myths, fairy tales, legends, folk lore. Although there may have been quite a lot of nonsense mixed in over the centuries, there are still some important insights into human nature to be found if one looks at these things with more than a casual glance.
So I hope your time here is not a waste but a chance to expand your mental horizons, to the benefit (ultimately) of those you serve not simply to council them on a spiritual level but also as a counselor when it comes to their everyday troubles and dilemmas.
And on another note, I believe "know thine enemy" is a maxim based on the idea that it you can figure out how your enemies think you can predict how they will act, and therefore be more effective in defending yourself and/or turning their own strategies against them.
I do not believe my time here is a waste. But the amount of time I spend here might easily call that assumption to question. I have no doubt that I am a better writer and communicator because of this time.
As to the "Know thine enemy" idea, I would say you are exactly right. But the Bible clearly teaches that no human is a match for the devil in his/her own power. The path to defeat the devil is to give complete control of your life to Jesus. So overmuch study of Satan is not considered necessary or even really good.
Karn: I would be very shocked to find out that more of Norse mythology was incorporated into the Christianity than Jewish mythology.
Also remember I walk with the Evangelicals, who for the most part would want to talk about an inerrant Bible and for whom the whole idea of myths growing into the Biblical tradition would be just this side of Heresy. (Parson resists the temptation to spend too much time on this, but would take it up in a PM if someone were interested.)