Is Bernie Sanders an atheist?

The “billionaire class is a very religious group of people,” and “their religion is greed,” Sen. Bernie Sanders (I-Vt.) said Tuesday, March 10, 2015 at the 2015 Alfred K. Whitehead Legislative Conference and Presidential Forum.

Greed is the religion of the billionaire class.
Greed is the religion of the billionaire class.

What is Bernie Sander’s religion and is he an atheist?

On the April 1, 2011 episode of ‘Real Time with Bill Maher’, the issue of pastor Terry Jones’ mock trial and burning of the Qur’an which resulted in protests and numerous deaths in Afghanistan was brought up. Sanders says to Maher:

“Well, I think this calls for your second film on religion.”

https://www.youtube.com/watch?v=4SpIP1zXwwk