PLEASE NOTE: This is a LIE. Please read the article above to see (click the picture).
The basis for all the conflict between Saudi's and Iran is the same as the conflict between Sunni and Shiite Muslims. It's ALL about who is going to establish the Caliphate for the worlds Muslims in the End Time.
Note how Islamic prophecy states, just as the Bible before it stated, that the Mahdi (the Muslim messiah) will establish the Caliphate from Jerusalem.
Sunni Muslims (Saudi Arabia is primarily Sunni) have been in conflict with Shiite Muslims (Iran is primarily Shiite) ever since Muhammad died back in the 600's. They both claim to be the true Islam and that they are supporting descendants of Muhammad to claim that the Mahdi will come from their faction.
This article, linked above, shows how the Saudi's are playing political games to ensure they get what they want through deception with the West.
There is no such thing as "moderate Islam". It is all a ploy to deceive the West and gain regional power so they can ensure that they get to establish the Caliphate.
This is also why ISIS is getting no support from them. ISIS has attempted to establish the Caliphate and claim it, but the leaders of Islamic nations want to use the Caliphate for their own purpsoses so they will not confirm it with ISIS.
For more information, see the following page: