Dueling Imperialists

The two greatest forces of imperialism in the world today is the West and the Islamic world. Those who truly believe and freedom and liberty should reject both. Its odd the way some on the left denounce the West and Christianity(not to mention Israel) for being oppressive, warmongering and patriarchal yet soft-petal the oppressive nature of Islam. How can one denounce one type of oppression and not denounce another form of it?