Evil, and for that matter Good in the same way, is not an imposition of an outside culture onto Germanic peoples. Germanic peoples had a native concept of Good and Evil.
Let’s break this down. Good and Evil are Germanic words. They aren’t coming into our language from Latin or Greek or French. Those words were already there before anyone else showed up to add things to our language.
An Evil etymology:
Evil comes from the Middle English evel, ivel, uvel, which in turn comes from the Old English yfel, which in turn cones from the Proto-Germanic *ubilaz, which in turn comes from the from Proto-Indo-European *hupélos and probably also from *upélos.
Evil has been with us from the beginnings of our language. The deepest down the roots go show it meaning to cause harm, treat badly, mistreat, harrass, or to go beyond acceptable limits.
A Good etymology:
Good comes to us from Middle English good, which in turn comes from Old English gód, which in turn comes from Proto-Germanic *gōdaz, which in turn comes from Proto-Indo-European *gʰedʰ-.
Good has also been with is since the beginnings of our language. The deepest roots of Good show it had a core meaning of to unite, be associated with, or to suit or be suitable.
So wherever you’re all getting the idea that Good and Evil do not exist in the heathen or Germanic world view, you are sorely mistaken. The cultures of the Germanic peoples were steeped in ideas about Good and Evil. But like most other things, they differed slightly in how they saw them.
The Bosworth-Toller has ample examples of Evil in Anglo-Saxon (Old English). It registers several different meanings including Evil or ill. Of people, Evil could be registered in a moral sense. Of objects or of things, Evil could show something could be bad or not good according to its kind in comparison to the rest. Further, Evil also was for that which was hurtful or grievous, including Evil spirits (Yfel wiht). For goodness sake they even believed in the evil eye (Yfel gesihð, literally evil sight).
The Bosworth-Toller is as amply rich in references to Good in Anglo-Saxon (Old English). Good in Old English has multiple meanings as it still does today. Good can mean having extra or enough of something, take a good handful; or it can mean being morally good, he was trying to do good; or it can mean something was good in comparison, each good tree bears good fruits; or it could mean good qualities in a person, he was good (courageous) on the battlefield; or it could be more nebulously moral, often good judgements have evil consequences; or it could just mean favourable, it was a good year and a good harvest. Each of these examples is either a rough translation of an actual Old English sentence or one that is similar to the thoughts expressed in a group of sentences. There are more uses for good but these show the basic understanding of Old English gód is no less varied than the Good of today.
And before you Norse people start thinking otherwise, you have Good and Evil too.
Old Norse was prone to using Illr (comparative to English ill) derrived from Proto-Germanic *ilhilaz, itself derrived from Proto-Indo-European *h₁elk-. They also had vándr which came from Proto-Germanic *wanh-. Vándr carried with it all the basic ideas of Evil that we find elsewhere and indeed is the ancestor the words for Evil in Danish, Swedish, Norwegian, Icelandic, etc. A rose by any other name would smell as sweet. The Norse then have a term for Evil and Ill just like Old English.
Good for the Norse is more directly related through góðr which is like the Old English gód also derrived from Proto-Germanic *gōdaz. This means that there is a direct link, a direct linguistic link to these terms.
Basically, there is a well developed concept in the ancient Germanic culture of Good and Evil and as we can see it encompassed much of our modern linguistic usage for modern Good and Evil. The ancient heathens were therefore not beyond Good and Evil, they lived in societies that deeply believed in these concepts.
That which is Good is that which is beneficial or desirable or that which is fitting. That which is Evil is that which harms or hurts or diminishes or goes beyond. These are societal values, they judged people and things and spirits and emotions by these values.
The only difference that I can discern is that there is little proof I have been able to find for ultimate good or ultimate evil. There is no ancient Germanic view of omnibenevolence or omnimalevolence. Those concepts smack of illogic today and had no foundation in Heathenry. That said, the absence of omnibenevolence does not preclude benevolence and the absence of omnimalevolence does not preclude malevolence.
Evil exists, Good exists, and Good is preferable to Evil, and that these existed in Heathenry as societal values. To deny Good and Evil as a part of that society’s religion and ethics and values is not historical despite how many people I see making this argument.