All other major religions except Islam have undergone modernizing, centralization, and moderation since their more barbarous beginnings.
Islam has not changed a whit in 800 years. Intractability is actually praised in Islam. The only solution is secular democracy - remove the threat of fundamentalists, allow power to reside in the hands of ordinary citizens and the religion will moderate itself.
Christianity did not have barbarous beginnings. Christ's gospel has been distorted or ignored by different rulers and nation states in the past two thousand years - the West struggles with his lofty ethical teachings and often falls short - but Christ did not practice or offer a program of holy war, incest, misogyny and intimidation.
I understand your point, but equating Christianity as it existed during its first four centuries of existence - presumably defined as its beginnings - with the first four centuries of Islam's existence finds that there is no parallel at all with Islam.