Re: The first Muslim secularist
^ From my understanding this is not what happened. Al Saud took allegience to the way of Ibn Abd al-Wahab without giving him any control over state. Today we see a legacy of religious police who do not step over the toes of the state police in Saudi and vice-versa.
After speaking with Saudi brothers they clearly state that Abd al-Wahab was given power over the religious lines and the Saud family had the state until much later were the state eventually strong enough to make the established religious elite subservient to their own cause and never do you see anything in their propagated books saying anything against the Saudi Monarchy. Whereas in Islam such monarchies are themselves a bid'a and yet these were allowed to continue.
Islamically, complete power needs to be given to the Ashura and they decide who is the Khaliph it is not done by heritage. Although the Shi'a differ in this view but the Saudis being Sunni should not.