Islam is divided into two main denominations, Shia and Sunni, these are fundamentally doctrinally irreconcilable and have a very long history of not liking each other very much. Sunni are by far the most numerous with 80 to 90% of all Moslems, Shia are 10 to 20%. But if you look where the geographic distribution is, the Shia have majorities in Iran, Iraq and Bahrain. In the last of these they are ruled over by a minority Sunni dictatorship which has been the cause of significant friction for years with the Sunnis disproportionately reaping the economic rewards of oil, this is now boiling over into open revolt.
In countries where they are the minority the Shias are also suppressed, this is especially true in Saudi Arabia. All of which leads to an ongoing regional power struggle between the Iranians on the Shia side and the Saudis on the Sunni side. They are engaging in a proxy war in Yemen and Saudi rushed troops into Bahrain to support the Sunni dictatorship against the Shia protestors.
In this power struggle the West is very firmly on the side of the Sunnis, happily giving massive support to some fairly unsavoury regimes whilst at the same time acting strongly against Shia regimes that are equally obnoxious. There is no doubt that we have been incredibly hypocritical with our illegal invasion of Iraq and sanctions against Iran whilst doing nothing about horrendous government suppression in states like Saudi Arabia and Bahrain. Even if they are massively rigged at least Iran has elections, which is more than can be said for our Sunni friends in the region.
Our huge bias in favour of the Sunnis is strange because the Shias are vastly more Western in their outlook. Iran is a far more civilised and developed country than Saudi Arabia, if we were to engage with them they would make a far more stable long term economic partner and there is far more chance that they would revert to some semblance of a secular pluralistic democracy.
Of course the reason for our hypocrisy is oil. Saudi Arabia is number one, it has reserves of 264 trillion barrels, 19% of the world total. But Iraq has 115 trillion barrels and Iran 137 trillion barrels. Also we are starting to find oil in more places. Canada has 175 trillion barrels, locked in oil shale that we are now starting to extract, Russia has 74 trillion barrels with much waiting to be discovered and Brazil is starting to discover and extract huge deep water reserves. Even the Falkland Islands sits in a huge oil basin and the USA has immense offshore reserves that they are only scratching the surface of.
Even if we became more even handed in our dealings between the two denominations of Islam the Saudis would still keep supplying us with oil, the House of Saud need our money to bribe their population, to finance their police state and to pay for hundreds of their princes to live the playboy life in London every summer.