Brian Ulrich reviews the basics:
The sectarian split between a Shi'ite majority and Sunni monarchy and minority matters, but not in a straightforward way. The country's rulers have played a game of divide and rule, one which seems to have accelerated over the past few years which have seen an increase in anti-Shi'ite discrimination. Presumably hoping to keep smaller the popular base to which they must dispense patronage while tying that base to them ideologically, the Al Khalifa dynasty has portrayed Shi'ites as potential Iranian catspaws and pointed to Iraq as an example of the negative consequences of Shi'ite democratic empowerment. What you see in the government's rhetoric is an attempt to cast the Shi'ites themselves as the sectarian ones primarily on the grounds of their Shi'ism, much like the Mubarak and Ben Ali regime claimed to suppress Islamic extremism.
(Photo: Anti-government protesters pray during a clash with Bahraini security forces near the Pearl roundabout on February 18, 2011 in Manama, Bahrain.on February 18, 2011 in Manama, Bahrain. By John Moore/Getty.)