Assassin's Creed Valhalla is full of choices that players must make throughout the course of the game, but not all of them are especially important. There are a few choices that will affect which ending players get, others will result in slight changes to the current quest arc, and a few have no bearing on the outcome of anything. It can be difficult to tell which choices fall into which categories, and so there's a bit of anxiety that hangs on every decision Eivor makes. In the case of whether or not to spare Goodwin in the Holy Day quest, the choice really doesn't matter.
Assassin's Creed Valhalla's Holy Day quest and the events leading up to it are a major turning point in the story, but aside from Goodwin's fate, there won't be any spoilers discussed. After players defeat Goodwin in a difficult boss battle, they are left with the choice of whether or not they want to kill or spare him.
As previously mentioned, this choice doesn't really matter in the grand scheme of things. It won't affect the ending of the game at all and hardly has any bearing on how the rest of this quest plays out. If players choose to kill him, Eivor will say a surprisingly quotable line as Goodwin kneels down to say a final prayer to his god. Afterwards, one swift strike sees Eivor kill Goodwin, and the powerful enemy will trouble players no more.
By contrast, if players choose to spare him, Eivor explains that they have use for him still. After threatening to take Goodwin back to the camp and force him to lead them to King Aelfred, Goodwin decides to take his own life. Though his reasoning is clear, he likely suffers much less pain going out this way than being tortured by the Vikings, it is still an odd end for the holy man. In the early days of Christianity, suicide was viewed almost universally as a sin, even if its intent was righteous or done to avoid further suffering.
Regardless, this means players can choose whichever option they want. Ultimately, this is more of a roleplaying moment for Eivor than anything else, so it is up to each player to decide how their Eivor would react to the situation. Choosing to kill Goodwin results in what is arguably the cooler cutscene, but it doesn't make a difference one way or another what players decide here.
Assassin's Creed Valhalla is available now on PC, PS4, PS5, Stadia, Xbox One, and Xbox Series X.