I stress again that there were several invading tribes, which entered a Britain of several tribes even on the coasts. The invaders in Kent, including the few Jutes to Eastern Kent, seem to have been elites who were somewhat more part of the trading network than warrior specialists in advance of land-seeking peasants, but the proportion changed as one went north. Customs of authority (dynastic versus consensus), economy (coinage vs gift-exchange), and alliance (marriages vs. community) look from archaeology to be somewhat different along gradients, so differences in religious practice likely were also.
Origins: Prior scholarship tended to view Anglo-Saxon paganism as a development from an older Germanic paganism. The scholar Michael Bintley cautioned against this approach, noting that this 'Germanic' paganism had "never had a single ur-form from which later variants developed."
There is an mportance of poetry in our understanding of paganism, but even at that, we are outsiders. Was
it primarily religious or adventurous entertainment? Lots of Christians go to see
Marvel movies now, after all, and Beowulf looks like pagan
adventurousness refashioned for Christian audiences. And don't overlook "It's
just fun." (See also Tolkien "The Monsters and The Critics," and CS
Lewis's "Hamlet: The Prince or The Poem." Both push back against the prevailing analysis of those works in their day with the simple and obvious reminder that people have liked them for centuries because they are whopping good stories. Appreciation does not imply belief.
Snorri Sturluson was a Christian, writing in an Iceland that had long been Christian. He wanted poets to understand the early references so that they could read the earlier poets and also perpetuate the stories. He tells stories in detail and is an imcomparable resource for Norse mythology. However, there are large separations between Snorri and Anglo-Saxon pagans in England. He is 700 years and 1000 miles away, just for openers. They speak related but not at all identical languages, and likely would not have been mutually comprehensible. He is Christian and his interpretation of events is filtered through that. And finally, he writes in poetry, which is, well poetic, and not always easily understandable even to insiders.
We know about sacred
groves among them primarily because of the later stories of Christians coming in and destroying them. When the Christian in question was not immediately destroyed, it was taken as a sign that the gods or spirits of those groves were not as powerful, leading powerful people, especially those who had hope of victory in battle, to convert so they could win. (And you thought your motives for conversion were a little weak?) This was also true of sacred wells, big trees, stones and stone outcroppings which we believe continued but know of no hierarchy.
The various Anglo-Saxons, though they were also Indo-European and thus descended from kurgan builders, regarded mounds as places of
unquiet dead, rather than friendlier ancestors. Of course that might not be much of a difference if one considers that they knew themselves to be intruders and reasoned "Well, those aren't our ancestors. They might not be happy to see us here." Nonetheless, throughout Brit but more in Wales and North where there was less
penetrance of Christianity, we see legends of knights under a mound or mountain, awaiting some signal to return and save their people.
There were Mjolnir pendants,
but these seem new among the later Anglo-Saxons, and thus more associated with the new Scandinavian invaders of the 800s. There is no definitive evidence any were simply A-S*. They show up increasingly over the next two centuries. But the more common something is, the more likely
it is to be a traditional decoration rather than an actual belief. Cf
Christian countries and the Christian or semi-Christian symbols of Christmas and Easter. For that matter, compare Christian countries and the pagan symbols of Christmas and Easter. None imply the least belief. It just wouldn't be Christmas without those.
Christianity not
supposed to be syncretic, and the official forms from monks or even
secular authorities forbid it, but it often is nonetheless. Kings especially seemed to go back and forth between Christianity and paganism depending on alliances. Consider the Franks Casket, with both the Adoration of the Magi and Weland Smith on it.
Was Europe ever really Christian? Festivals and practices which now survive across the Isles and are claimed to be ancient and pagan cannot be
certified as earlier than 1000, and even then, we don't know what
meaning they had. If Church authorities left it alone, what does that
mean, that they feared blowback from the citizenry, or that they thought it was just a harmless old custom?
When The Vikings came in, we can only say for certain that Thor and Odin crossed the water with them. Yet we have seen at least some evidence of other Norse-related gods before that. When Saxon and Danish followers of Tiw encountered each other, what was the result?(Oh, sure. We know that guy... or "Y'know,
that looks a lot like a festival we used to have back in Denmark..") Local customs can persist for centuries even when they are not understood the way the were even a few generations ago. Look at how the Christians of the time split over things as small as what a tonsure should look like or how to calculate the date of Easter. There's no guarantee that Frigg-worshipers would have welcomed each other as long-lost cousins. Sometimes people get killed or whole villages get wiped out over such things.
I should mention St Aldeberge/Bertha, the Frankish princess who became the first Christian queen in England, at Kent around 600. She agreed to the marriage only if allowed to keep practicing her faith and bring a priest/confessor. Aha! A foot in the door. And also Eadburh, a Christian daughter of the pagan Penda about the same time. I keep hoping a granddaughter will decide to write a history paper about one of those.
Last bits that don't fit in elsewhere: I haven't discussed how powerful the concept of wyrd might have been among them, or if the triple goddesses owe anything to the Norns or Fates. I will note that a difference with the neopagans is the difference of Magic versus sacrifices. Magic and sacrifice are not the same thing, though from both a Christian
and a modernist perspective they look similar. Magic, which is more
neopagan, seeks to change events and is more concerned with individual
will and power. Sacrifice is more about maintaining order between the
visible and invisible worlds and creatures, and is more community based.
*With all these tribes perhaps we should designate them ASFFJ+