modern Christianity has made further positive steps to turn their back on more of what is wrong in the Bible ... There is no reason Islam cannot also progress down a similar path - JWFacts
One of the blocks to reform is that the quran is held to be directly dictated by Allah. Every single letter of every syllable is his word. Where there are conflicting statements later sayings supercede earlier ones.
As Muhammad became more powerful in Medina his pronouncements became more aggressive towards infidels replacing the conciliatory sayings of the Meccan period.
Many western terrorists were radicalised by Mullahs who introduced them to the quran in their own language. Previously they had only learned to recite verbatim in Arabic. It is a poisonous book. The Hadith and Sira offer no way out either.