is there a common theme that connects the books that liesel stole?

I think the power of language is one common theme. Death seems to be another.

Here is a great quote about Liesel's love / hate relationship with the power of words,

“I have hated words and I have loved them, and I hope I have made them right.”

The common theme connecting the books that Liesel steals would be that they tell the story of her life. Each book tells a part of her story and represents not only who she becomes as a person but those she loves as well.