Chancellor Angela Merkel told lawmakers on Monday that her government had decided to break with a taboo on delivering weapons to conflict zones because Germany and all of Europe faced a security threat from the extremists of the Islamic State in Iraq and Syria. Ms. Merkel and top ministers decided Sunday to deliver thousands of machine guns, as well as antitank missiles and armored vehicles, to Kurdish forces battling ISIS in northern Iraq. The deliveries — from existing German Army stocks, and worth an estimated 70 million euros, or almost $92 million — will take place in stages in the coming weeks, the Defense Ministry said. On what was the 75th anniversary of the Nazi invasion of Poland, Ms. Merkel went before Parliament on Monday to justify the arms decision. She evoked scenes of mass terrorism and killings in the Middle East, and said of ISIS, “Anything which does not conform to their view of the world they simply expunge from the scene.” In sum, she said, “A religion is being abused in the most terrible way.” She added, “The far-reaching destabilization of a whole region affects Germany, and Europe.” Before going into detail on Iraq, she recalled that Nazi Germany invaded Poland on Sept. 1, 1939, starting a war which, together with Nazi crimes, caused millions to die. “We Germans will never forget this,” and it has underpinned post-1945 Germany’s reluctance to enter into conflict, she said. But in the case of ISIS, she argued, her government believed it had to make an exception. The parliamentary debate on the weapons deliveries was symbolic, since the government can decide to deliver arms where it wishes without the authorization of legislators. In a nonbinding vote, lawmakers overwhelmingly backed the government.