Abd-ul-Wahab was an incarnate whirlwind
of Puritanism against the prevailing
apostasy of the Moslem world. The sect which
he founded and which took its popular name
from him was a protest against Moslem idolatry
and superstition. It stood for no new doctrine,
but called back to the original Islam. Wahabiism
was an attempt at an Arabian reformation.
Yet so far from giving any progressive impulse
to the Mohammedan cult, it has proved the most
reactionary element in the history of Islam.
This purely Semitic and unique movement, with
all its energy, has produced nothing new; it
has been directed exclusively toward the
repristination of the old Moslem monotheism.
The history of the sect shows that a reformation
of the Moslem world by a return to primitive
Islam (in theory and practice) is an
impossibility, even when aided by the sword.
Samuel Zwemer, the Disintegration of Islam, ch 2. (p 77)