That's because it is a lie. More people have been killed by state-sponsered atheism in the last 100 years than all the Christian wars combined.
There are lies, damned lies, and of course, statistics. Try reading some of the history of Europe, the Middle East, and Asia. You might find that many deaths resulted from human prejudice and greed, much of it state-sponsored, and almost always incorporating the ever useful component of "religion".
Has state-sponsored atheism killed more people? Perhaps. Has religious extremism killed a higher percentage of the population at any given time in history? Most probably. In the absence of powerful atheistic states, will future deaths reflect the economic, cultural, and religious divisions? Most certainly.
Including the current dilemma? Absolutely, according to Mr. Hagee.