Excerpt
That these types of crimes and activities distort the true image of Islaam. And this is in reality oppression. Oppression to Islaam and the Muslims, because the people now, at this point, if it is said to them that these bombings are from Islaam, then it will result in the people hating Islaam. And they will hate the Muslims. And they will run away from Islaam. And they will have a feeling towards Islaam of enmity and rancour. Likewise these crimes involve lying upon Allaah and lying upon the Messenger.

It is obligatory upon the Muslims, all of them, that they honour their agreements, and they honour their contracts, and that they speak truthfully when they speak. The true Muslim is not treacherous, and he is not deceitful, and he does not lie, and he does not oppress. This is what Islaam teaches and this is something this is clear from the religion. As for those activities such as bombing and what is similar, they distort the true religion of Islaam and they ascribe to Islam which in reality is not from it. Because verily the true Muslims, those who understand the reality of the religion of Islaam, in every place, they hate and reject and they criticise these criminal acts and they warn against them. And they warn against those people who call to these acts.

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http://www.islamagainstextremism.com/articles/klpog-islam-is-against-terrorism-and-the-islamic-legal-rulings-on-terrorist-acts-and-those-who-commit-them.cfm