True enough, Islam was born in isolation on a virtual island so that separation of church and state was never considered. Accordingly it became liberal or fanatical due to 100% concentrated power.
Christianity, conversely, was born within the Roman Empire so had to compete with the Roman Gods and Emperors intellectually. This created a strong intellectual tradition and tension between church and state with the state being left with half the power only. When the Vatican was built, for example, it featured the famous Schools and Athens fresco which featured both Plato and Aristotle indicating that the church saw its role as in part academic, as bringing wisdom forward, and as an intellectual alternative to the concentrated power of the liberal state.
No surprise then that Christianity being conservative out performed Islam being liberal.