English Version of My Article: Why are most Shias with the opposition and most Sunnis with the regime in Bahrain? 
I don't think it's a sectarian issue. The government is not against shias; it is against any challengers of power.
So why are the majority of challengers of power Shia not Sunni?
Here's why in my point of view:
* The Sunni religious authorities (i.e. Muftis) and religious scholars in the Gulf are either appointed by or affiliated with the Government/Ruling families and are virtually government mouthpieces. This lack of independence diminishes the credibility and perhaps even the legitimacy of these religious scholars. When a religious cleric becomes a government employee, the relationship becomes that of a superior and a subordinate and consequently all the religious preaching and fatwas get issued to serve the interest of those in power rather than serving the religious principles they claim to be advocating. The banning of political demonstrations in Saudi Arabia by the highest religious authority in the kingdom is a case in point. Nowhere in Islam are political demonstrations condemned; if anything they are encouraged. Revolting against injustice is in fact a core Islamic principle.
* The stance of Sunni religious scholars against demonstrations and pro-reform movements vary but the bias in favour of those in power is overwhelming. The majority of Sunni religious figures in Bahrain and the region are in fact pro-government. The absence of independent Sunni religious figures is a serious ideological issue for Sunnis in the region because the majority of Sunnis in the Gulf are deeply religious people and in need for a credible and trustworthy religious authority to look up to. This however is not possible with most Sunni religious scholars fully affiliated with the existing power structures. It is difficult for the layman to accept the absence of such an important source of religious legitimacy so he simply justifies their political and religious positions and stands by them even if they are far from fair and just.
* Of course, the generalization that there is no Sunni opposition is wrong. The reality is that there is no religiously moderate Sunni opposition. The majority of Sunni opposition in the Gulf is either secular/leftist/liberal or extremist/salafist. As a result, moderate religious Sunnis do not have the choice but to follow the pro-government religious figures (e.g. Abdellatif Al Mahmood)
* In addition to all the above, the tribal mentality and the loyalty to the tribe is still very common in the region.
* There is also this concept of 'Wali al Amr' or Guardianship. This widely held belief amongst Sunnis that one has to obey his Guardian (i.e. ruler) makes political opposition amongst Sunnis less likely. 
* Also, the economic standard of living of many Sunnis in the Gulf is relatively high compared to other Sunnis in the Arab world and compared to the Shias and this has probably made Sunnis less inclined to demand their political rights and participate in reform movements. (worth re-stating that the majority of Sunni political activism since in the 50s, 70s and later and before have all been very secular, they were popular at the time because religious sentiments were less so)
* Finally, the legitimate or illegitimate fear of future alternatives. In Bahrain, for example, the Sunnis fear the scenario of Shias coming in power and the possibility of instating inequality against the Sunnis (as is the case in Saudi and Iran with the Shia and Sunni minorities respectively)
All the above leads to the following status quo:
* Absence of political awareness amongst Sunni youth (and thereby lack of political and pro-reform activism)
* Overwhelmingly pro-government stance of the majority of Sunnis
* Sunni opposition is either liberal/secular/leftist or extremists/salafist
Now, what about the Shias:
* Given that the Shia constitute a majority of unequal rights in Bahrain; it is only natural that the level of their political activism is greater
* However, the main problem with the shias is this concept of wilayat al faqih (which encompasses religious and political authority of the waliy al faqih)
* Another problem is the concept of emulation (taqleed) in Shia ideology. Although the religious emulator holds only religious and no political authority (unlike the waliy al faqih); the widespread photos of Shia religious emulators and figures in shia mosques, husseiniyas and other public gatherings creates that lack of trust among sunnis.
* In addition to all that, actual differences in religious beliefs and practices between Sunnis and Shias such as the view of Shias towards some of the Prophet's companions, their exaggerated expression of grief and seemingly 'weird' husseini practices during Muharram (such as self-flagellation) deepens the cultural and social gap between Sunnis and Shias which makes it difficult to create political and social solidarity in real reform issues.
But Is the Sunni fear of Shias legitimate? 
The answer is no. There is no suggestion or evidence that the demands of Shias are sectarian demands. All the demands are fair and legitimate and will benefit all Bahrainis.
The fear of Wilayat Al Faqih is exaggerated and unjustified. Although Iran may have had the ambition of exporting the revolution (and Wilayat al Faqih) at the beginning of the revolution but these ambitions have vanished. Today, Iran doesn't have the desire nor the ability to impose that nor do the majority of Shias in the Gulf have that desire or conviction.  In Bahrain, for instance the Shia majority follow/emulate Fadlallah and Sistani, who does not believe in the concept of Wali al-Faqih. As for emulation, it is purely religious guidance which doesn't differ much from the Sunni model. All religious groups have external, regional and international figureheads and affiliations.
Final word
Clinging to one's religious sect becomes stronger when rights are not protected and the identity is threatened. If these rights are respected and protected, the Shias or any other minority will have no problem in rallying around the existing regime and abandoning any sectarian affiliations that deepen the split amongst members of the same community.