What Theology To Read?

Operating under the "Know Thy Enemy" premise, I've been thinking I should read some of the more important works of theology to have a better handle (and/or more ammunition) on "sophisticated" religion. I'm assuming the something by Paul Tillich, Teilhard de Chardin, and Soren Kierkegaard would be important but I don't know which ones.

What other works or authors exemplify the "best practices" of theology as it is currently practiced? Is there a good introductory survey work I should explore? At the moment, I'm restricting my research to the Christian religion. Judaism and eastern thought is on the list for later.