Vikings 10 p.m., History
One of the coolest things about “Vikings,” which returns Thursday for season four, has been its ongoing religious themes. The show is a beautifully filmed saga with lots of political game-playing and action sequences, but it’s also a look at the conflicts between paganism and Christianity and a few people — including the show’s hero, Ragnar — who cross the boundaries between them. When Ragnar takes a Christian monk named Athelstan under his wing, and they become close friends, he opens his heart to Christian possibilities. Athelstan, too, goes through his own flip-flops. The show gives us the epic religious battles between worlds, but it also gives us the intimate side of religious tension and power.
Last season, Floki the boat builder, played with just the right amount of craziness and vengeance by Gustaf Skarsgård, son of Stellan and brother of Alexander, killed Athelstan. How will Ragnar deal with that? All I’ll say here is that he will indeed deal with it, which gives Skarsgård an opportunity to act up a storm. Also this season, the story line jumps with more regularity to Wessex and Paris, where Ragnar’s brother, Rollo, is now married and trying to fit in.
I feel about “Vikings” the way I feel about “Shameless.” It’s consistently well-made, entertaining, and held aloft by thought-provoking ideas.