Spe Salvi,: a sort of “Greatest Hits” collection of Ratzinger’s most important ideas

John Allen summarized Benedict XVI's main themes as:

• Truth is not a limit upon freedom, but the condition of freedom reaching its true potential;
• Reason and faith need one another – faith without reason becomes extremism, while reason without faith leads to despair;
• The dangers of the modern myth of progress, born in the new science of the 16th century and applied to politics through the French Revolution and Marxism;
• The impossibility of constructing a just social order without reference to God;
• The urgency of separating eschatology, the longing for a “new Heaven and a new earth,” from this-worldly politics;
• Objective truth as the only real limit to ideology and the blind will to power.

I'd say he's six for six. I doubt Allen's self styled "liberal" and aging readers are pleased.