Marx didn't invent dialectics: it's actually a part of human nature.
1. When you are not in power, you are nice to gain power.
2. When you are in power, you are nasty to keep power.
Islam is just like this. The Koran is written with this basic ploy in mind. Historically, the 'Suras' were 'received' by 'Mohammed' in two places: Mecca (Makka), and Medina. In the former, he was not in power, just starting out. After he was kicked out, he and his followers went to and took over, Medina.
The composition then has what are called 'laws of abrogation', where the later 'inspiration' cancels out the former (Mecca) rules. In short, the nastier, in-power Suras (chapters in Koran) supercede the nicer, out-of-power Suras.
So it becomes real important to know if a given SURA is pre- or post- Medina. Since the actual Koran's Suras are instead arranged descending-length order (why, who knows), then you need a chronological table to know which ones are pre and which ones are post-Medina arrival. Any hardback Koran should have a preface telling you whether pre- or post-Medina. It's not always clear from the online Korans.So anything in the post-Medina suras which contradicts the earlier ones, REPLACES the earlier text.
That's how you 're supposed to read it.
So here's the chronology
. All suras after 86th in order
, are Medina suras. So any material in those later suras which contradicts the earlier ones, REPLACE the earlier ones.
Example: the Cow Sura, officially #2, is the first of the Medina Suras. It is also extremely violent. So just read it, to know why the jihadists claim (rightly) to be more 'true' to Islam. The actual Sura is a brilliant piece of work satirizing the Exodus when Moses was given the law. (I wrote a commentary on it which is indecipherable now, http://www.brainout.net/Cow.htm . What I wrote makes no sense if you're not very familiar with the Cow Sura.)
A less-trustworthy chronological source is here at wikislam
. All its links don't work.
The link I had to Mughal's research was lost in the old FFI forum (FFI is often attacked), but here's a thread by a wonderful user I remember, yeezevee: he's trustworthy: http://forum09.faithfreedom.org/viewtopic.php?f=21&t=468&p=5796&hilit=Revelational+Sequence#p5796
WARNING: if you'll google and look for sources, do NOT go to any source sponsored by Muslims. They track you. Instead, choose some western source and be sure your cookies are set to block or conditional, or do the search in a library or on some public computer so YOU cannot be traced.
Or, ask at Faith Freedom International, here
(that's where I got the first link).