Yes, it all sounds a bit crazy, Roy, when there is supposed to be one God. But Muslim theologians look at the matter also from the perspective of what they perceive to be the examples of living according to their Prophet, Muhammed.
I did (partly) cover this matter on page 1 of this topic, and this is what I said:-
A lot of Sunnis and Shia like to dismiss the theological and historical differences between their sects, but, as in Christianity, there are some hard-nosed leaders who like to perpetuate the differences.
And what is crucial in this debacle in Iraq - and one completely missed by Bush and Blair - is that apart from the fact that the three major divisions in Iraq (Shia, Sunni and Kurds) virtually all live in distinct areas and therefore do not logically constitute one country, the historical differences between Shia and Sunni really emanated in the country we now call Iraq some 1300 years ago, and is why Kerbala is of such religious significance to the Shia.
The main difference between the two sects is that the Shia believe that the leadership and spiritual understanding was given by Prophet Muhammed to his son-in-law 'Ali and his progeny, but the Sunni tried to obliterate that familial authority by anihilating 'Ali's progeny at Kerbala.
The area has seen a huge amount of violence ever since.
Some say that the present day Aga Khan [an alleged descendant of Muhammed] is the true leader of the Shia, but there is considerable difference between his party (the Isma'ilis) and the rest of the Shia (and, indeed, the Sunnis). The Isma'ilis are very progressive.
There are plenty of sub-sects of both Sunnis and Shia, and it is the highly puritanical Wahhabi Sunni influence of Saudi Arabia that influences the thinking of al-Qaida. The Druze of Lebanon (who - over the last 2 or 3 decades - have been publicised about their militant activities) are in fact descendants of a Shia break-away sect in the middle ages (at the time of the Crusades).
The word 'jihad' crops up a lot, as I'm sure you know, Roy, and it is the lesser form of jihad (which is fighting physically for Islam) that al-Qaida have adopted. Those that understand Islam more fully know that the greater jihad is fighting one's self - the base instincts of the self; making one's self more spiritual - not fighting other people.
There is a strain of deep spiritual thinking in Islam that is known as Sufism. Some of the greatest Sufi teachers have been so-called poets such as Omar Khayyam (whom you may have heard of) and (particularly) Rumi. But, again, the more extreme hatred-oriented members of Islam often deny that Sufis are Muslims.
I could go on and on, Roy, as I am blessed with a lot of knowledge about Islam, religions in general and other psychological systems. I say that as humbly as possible. Islam is a wonderful religion in its purest teachings, but it has been made to look warlike and unattractive by extremists. In some ways the existence of sects in Islam is unimportant, but to understand the politics of the Middle East, a broad knowledge of the differences between the Sunnis and Shia is quite useful.
As far as Saddam is concerned, his recent devotion to al-Qur'an mocks his previous attitude towards his fellow Muslims. Any Muslim (and anyone else) who stood in his way was to be disposed of come what may, and he regarded the Kuwaitis as 'fat cats' that were the beneficiaries of western influence. Don't forget that Kuwait was once part of Iraq. Iran is predominantly Shia, and so they were ripe for annihilation by that fact alone. Saddam was nominally a Sunni supported by the minority Sunnis in Iraq.
I hope all that helps, Roy.