Hi guys! Thanks for all of your help and replies! Here's the final chapter!
March 1075, Immediately after the invasion of Denmark
Here's the realm at this point (This was one of the four screenshots I took)
Erik sat on the throne of the former king of Denmark, in the great hall of the castle. HIs men were feasting after the long campaign. Things were going well for him: He had plenty of land and men, and support. He had just two problems left: firstly, the legal traditions in Sweden mandated that a king must wait five years before passing another law, and currently he couldn't dispossess the Christians or hold much land, or even nominate a successor from amongst his sons as the ancient customs dictated. The second problem was that he had lost too much money in his campaign, and had no emergency reserves. The solution to his problems didn't come to him for a few minutes, and he only realised the easy way when some rowdy warriors complained that since the booty was on the slim side, they'd go to the kingdom of the Franks to relieve them of some coin.
"Of course, a raid is the obvious solution! Then, I can wait out the three remaining years while taking enough loot too choke a dragon!" he said aloud, albeit quietly to himself. He continued, a little louder for the men to hear. "Men, riches were in short supply on this invasion for some. Any man who wishes to increase his wealth, I will lead a great raid to the West!"
He was met with great cheers from the feasting men.
The following morning, he assembled his warriors on the ships and he left for the first target, Frisia. After a close shave with the local garrison, they moved on to Northumbria and then to Wales, and finally to Ireland. He made sure to burn down the temples on the way and perform the traditional Odin-glorifying dance in front of the Christian monks (The Odin-glorifying dance was pretty much performing the moonwalk/take the L dance from on the longships while mooning and saying "Neener-neener, Odin's swell, your gods smell!" (this was the only plausible explanation I could think of for why exactly burning down temples increase the moral authority of the Germanic faith)).
While in Ireland, he remembered his father. The man who had given him his lands (even though he couldn't make him king) and who raised him as a good pagan. He decided the best way to remember him was with a runestone, and he would leave it in Ireland so that his and his father's names will be remembered.
In the end, he returned with about four hundred pounds of gold and he made a great name for the Germanic faith (if a great name means stealing from the most vulnerable sectors of society and rubbing it in afterwards, and fleeing like wimps whenever actual soldiers show up). When he returned to Sweden, he announced his intentions to change the succession laws to the old ways (of course he had to butter up a few nobles first). He then announced that (with the help of a few bribes) he had changed the laws to allow himself to relieve any Christian noble of his lands, and it would be perfectly legal. He started taking from the small nobles who would cause less trouble, and he gave to noble Germanic nobles. A few of the major dukes opposed Erik, but mostly they gave up their titles.
Now, Erik had one more thing to do: reform the faith. He summoned all of his priests and vassals to discuss how the faith worked and how to create a better Odin-worshipping system (I also forgot to mention an earlier conquest of Nidaros, that should have happened just about after when Erik made himself king).
Erik, in his old age, wanted to take back just a small piece more of the Germanic lands: Viken, the home of the noble Harald Fairhair, should belong to the pagans. He gathered his men for a holy war. The war was long and uneventful, and many Christians joined in to defend Norway. But in the end, Erik prevailed.
Finally, he stood at his castle in Uppland, and was satisfied to see that there was no forgiveness going on, only Odin worshipping.
"If only Emundr could see this" he sighed to himself. He looked to his courtyard, where his two sons sparred energetically but not with hate. Unlike most royal Norse brothers, there was no hate between them. He looked to his daughters, one was playing some sort of a game, another was sitting in the shade of a tree, and the eldest... he peered around, until he saw his daughter sneaking away with one of the village boys behind the barn! What nerve!
But Erik had made it. For centuries to come, the Swedes would not be overcome by the eastern gods, and Erik had ensured that the Viking age didn't end here.