What is the role of the Mosque in Jihadism?

What role are the over 3000 Islamic mosques playing in making a Manhattan type bombing or another 9-11 possible in the US? It only makes sense that the Imams and the teaching in the mosques are either telling American Muslims it is a sin to destroy and murder or they are telling them how to best murder and destroy. What is the role of the Mosque in Jihadism?