Letter - Two parts to Koran
Recent letters with Koranic quotes have caused some confusion.
Some letters have quoted peaceful verses, and some have quoted more warlike ones.
The explanation is that there are two parts to the Koran, the earlier part written when Mohammed was in Mecca, had few followers, and naturally appealed for converts peaceably.
The second part of the Koran was written in Medina, when his numbers and confidence had grown, and is more aggressive.
This allows commentators to choose their quotes according to how they wish to portray Islam.
The Koran itself deals with the confusion this creates – "We always abrogate or nullify the earlier verse and replace it with the later" – 2.106.
Thus "Do not fight unless attacked" is replaced or nullified by verses like the well-known "Slay the infidels wherever you find them", and "There must be no compulsion in religion" is replaced or nullified by verses like "There must be no rest from jihad until all the world is Muslim".
The above principle of dealing with contradictions is known as "progressive revelation" or "nasikh" in Arabic.
I trust this clarifies the issue.