From a Lutheran pastor who converted to Catholicism, responding to http://jmm.org.au/articles/8073.htm:

Theology: This isn’t just because he is now Pope, but Ratzinger has to get a guernsey there somewhere. His classic was written in 1968 called “Introduction to Christianity”. I have been reading it now for almost a year. You have to take it in bite-size chunks and chew well. Best statement of the Theology of the Cross I have ever found there (see http://www.cumecclesia.blogspot.com under the blog “One God and One Christ”).

Church History: On the Reformation the book simply called “Reformation: Europe’s House Divided” by Diarmaid MacCulloch is better than anything I was ever served up at the Lutheran Seminary. A sort of “what really happened” approach which leads one a little closer to understand “what it really was all about”.

Merton. Yes. It doesn’t get much better than “Seeds of Contemplation”. There’s a lot before it that was worse, and a lot afterwards that is questionable, but it is very good.

And of course, everyone will wonder what happened to Tolkien in your list, but there it is. Not everyone is a fan!