Okay you guys, here is the thing about Athelstan. (OH GOD I AM ABOUT TO MAKE A COMMENT OF MINOR SUBSTANCE ON TUMBLR, WHY.)
There is a deleted scene from the series where Athelstan talks about his past. In this clip, he tells Gyda that his family left him at a monastery when he was very young, since he was the youngest of a large family and they could not support him. His family then all died from a fever. So he’s an orphan who didn’t choose the Church. He’s a young man who was GIVEN TO THE CHURCH. He wasn’t called to God, he was raised in the church with no other choice and no other option. His faith is central to him because it’s all he’s ever been taught. Even (one would imagine, seeing as he would not have travelled alone) on his mission work, his focus was on conversion - pretty much the opposite of being open-minded about another culture. The Catholic Church has been his entire life, his entire existence, until he’s kidnapped and taken to Scandinavia.
There is worry about Athelstan’s agency from a lot of people in fandom, since he is a slave to Ragnar and Lagertha. Issues that people have in terms of a sexual relationship, and also in terms of his lack of choices in this new life. I am not disputing that this is problematic! But I would like to say that I think that Athelstan, in this new land, has more freedom in some ways than he has ever had. He’s in a place that is new, and Ragnar doesn’t discourage his curiosity. He is learning about the world, about politics and power and death and war and love and what a FAMILY looks like and loyalty and joy and gods that aren’t his own. He’s learning about sex, in a really sex positive environment. We have never seen them coerce him into anything, aside from Ragnar’s interrogation when he’s drunk. He’s learning about how people are good and bad everywhere. He’s asking questions and questioning what he’s been told all his life, and in a home where it is SAFE for him to do so.
This scene, of the gif set, is proof (to me) that Athelstan is realizing this. It’s proof that he is learning that the life he left is, in many ways, more constrictive than the one he’s living now. Now, I know it’s touchy to base a chunk of characterization on a DELETE SCENE, but oh, man, IT’S A PERFECT SCENE and explains SO MUCH about the journey he’s on in the show.
It doesn’t take away the issue of Athelstan being a slave, but I think that in HIS MIND, the life he’s sharing with Ragnar and Lagertha is SO MUCH MORE FREE than the life he was taken from.