Saudi hosting anti-terrorism for islamic coalition: http://www.bbc.co.uk/news/world-middle-east-35099318
A positive step if it assists the stabilisation. However if penetrated by terrorist groups it could also act as a hub for coordination across all the coalition states and beyond.
The good side of it is it is effectively a statement by the religious leaders in normalising the approach and interpretation of islam. The negative side is if that approach drives for fundamentalism and cold shoulders moderates.
A major caveat being that all atheists are terrorists in their eyes.
Saudi Arabia never does things without some measure of extremism themselves.