You see, you can't simply say, "Lets open a dialog with them." Or "Our message doesn't penetrate deep enough." Oh, they hear your message. The majority of muslims - the 80% - hear it clearly enough. Its just that they choose to ignore it - either out of apathy, fear, or hate. The problem doesn't lie with the West's lack of effort. The problem lies with the muslims' lack of will.
Before you can even start to have a dialog with the muslim world, you need to eradicate/eliminate/annihilate the top 10% of the terrorizing 15%. Only then will the civilized world have a chance to be heard by the rest of the population.