The key difference here imo, is that the Bible doesn't imply and never says anything even close to something like, "All interpretations are correct in the eyes of God". The Quran does, which means moderate and peaceful Muslims, if they follow that tenant (They usually do) never rebuke extremists or call them out. The moment you stop holding yourself or people in your group accountable, even if only by social ostracization, you allow yourself open to the absolute worst kinds of corruption.
Don't get me wrong, the Christian churches are definitely corrupt and have been open to corruption for a long time, but usually not nearly as bad as in Islam, and when some group like the Westboro Baptist Church shows up most Christians will rebuke them, turn their backs, etc... When was the last time you heard a Muslim talk shit about ISIS? I bet you even if you have(Which I seriously doubt), it's not nearly as often as you'd hear a Christian talk shit about Westboro Baptist.
If you're part of some part of organized group and extremists are ruining your image and making other people's lives turn to shit, or making other people extremely uncomfortable, HOLD THEM ACCOUNTABLE. Otherwise your entire group is liable.