You answered your own question. But I don't think you realized it. Don't blame you. The answer is rather heinous.
Liberals don't believe terrorism is as large a threat to this country for one simple reason. Liberals hate this country. Liberals hate capitalism. Liberals hate personal achievement. Liberals want to see this country, as it exists now, be destroyed so they can remake it in their image.
If you are personally achieving, you don't need a big government subsidizing your life. Capitalism calls for individuals to follow their own capabilities and greatness to success not to follow the government to success. Liberals need as many people as possible totally and completely reliant on government, on liberals, for their very existence. It is the ultimate source of political power. If the entire country relies on you for food, fuel, housing, transportation, your very life, you will never be voted out of power.
Liberals are socialists. It is that simple. Ever noticed how you cannot be a happy liberal? For liberals to succeed, to gain power, to win votes, they have to demonize someone. An American is always evil. Big Oil. Big Pharmaceutical. Big Industry. Big Wal-Mart. They demonize Bush, they demonize republicans, they demonize American workers, they demonize the health care system, they demonize the insurance industry. Everything. Anything that gives people control of their own life is evil and needs to be destroyed.
Liberals don't want this country physically destroyed. They don't want New York wiped out. They don't want Texas to fall into the sea. What they do want, however, is all vestiges of capitalism, conservatism, individualism erased. That is the same goal Islamic terrorists are after. Ever listen to a Bin Laden tape?. Ever read a Ahmadinejad letter to America? they mimic liberal talking points. They all say the same thing. They make the same points. They believe the same things.
http://www.cnn.com/2006/WORLD/meast/11/29/ahmadinejad.letter/
Just read it. Everyone. Iraq, Abu Grhaib, Gitmo, Palestine. Its all the same. The exact same thing Democrats in Congress say. The exact same thing the left in this country says. That is no coincidence.
http://kutv.com/topstories/local_story_250234504.html
Again, read it. The "unjust" war in Iraq, the Bush Administration lying, the references and comparison to Vietnam, the idea that terrorism is our fault because we meddle in the world, even calling President Bush a terrorist. Again its all the same. The same crap being spewed by the left in this country.
That is heinous truth. Liberals don't see Islamic terrorism as threats because they have the same agenda. Its the only logical conclusion. If you're a liberal, its the only end to the thought process, the only question left: Why are the "terrorists" a threat if they are doing us a favor?
EDIT: Really wanted to bring this into it after reading one of the responses. War for oil. Heard that before. The left said the same thing when we liberated Kuwait. They didn't want Kuwait liberated. So now they spew the same nonsense again. But here's a question: if its all about oil, why not Qatar? Or Saudi Arabia? We already have troops there. If we just wanted to control oil why not just take control of any of the countries we currently buy oil from?
War for oil. Utter nonsense and vile lies that only serve to cheapen human life and human accomplishments.