"While other scriptures contain contradictions, the Koran is the only holy book whose commentators have evolved a doctrine to account for the very visible shifts which occur from one injunction to another. No careful reader will remain unaware of the many contradictory verses in the Koran, most specifically the way in which peaceful and tolerant verses lie almost side by side with violent and intolerant ones. ...To get out of this quandary, the commentators developed the doctrine of abrogation, which essentially maintains that verses revealed later in Muhammad’s career take precedence over earlier ones whenever there is a discrepancy.
....
"But why the contradiction in the first place? The standard view is that in the early years of Islam, since Muhammad and his community were far outnumbered by their infidel competitors while living next to them in Mecca, a message of peace and coexistence was in order. However, after the Muslims migrated to Medina in 622 and grew in military strength, verses inciting them to go on the offensive were slowly “revealed”—in principle, sent down from Allah—always commensurate with Islam’s growing capabilities."
Explaining how Muslims are good citizens until they form a majority. At that point they seem to me to become as conquerors. TD