Atheists: Why do Christians believe that the definition of a liberal is "Anyone who disagrees with me about something"?

If by a "Liberal" they mean someone who looks ahead and not behind, someone who welcomes new ideas without rigid reactions, someone who cares about the welfare of the people-their health, their housing, their schools, their jobs, their civil rights and their civil liberties-someone who believes we can break through the stalemate and suspicions that grip us in our policies abroad, if that is what they mean by a "Liberal", then I'm proud to say I'm a "Liberal.

John F. Kennedy, Profiles in Courage

They can't seem to validate their views in any other logic.

Many reasons, but mostly to demonize anyone even remotely 'leftist' as unpatriotic, against the Constitution, against free speech, blah dee blah. You've seen the answers here. Also, many Christians are not used to defending what they say or having to explain the pat blurtings they blurt out so complacently. It can be frightening and flustering to have to delve into why you said or wrote what you said or wrote. 

It's a lot easier just to point and screech that it's liberals who don't like anyone disagreeing with them blurk blurk blurk. Instead of facing whatever has been said, examining that and going from there. Which would be reasonable and logical, eh? Yeah. 

You must be a liberal because I disagree with that.

Well, they do believe all sorts of silly crap, don't they....this is no different.

I mean, you should hear some of the crap that 2-hunter hitches his wagon to.

This atheist looks at conservatives as resistant to change.   Religious people and older people fit in that category...

Liberals and youths are open to new ideas...

I'm a liberal 80 year old ...     

Because if they knew what "liberal" actually meant they'd realize they worship one.

Not all people who identify as Christian are that thoughtless.  Indeed we are thoughtless if we believe that.  No matter who is doing the labeling of individuals in order to easily sort people into friends or foes, it does everyone a disservice.  I think we are all family who owe each other a duty of inclusion and care.  No excuses.

Asking a fool to explain why a Christian believes the definition of a liberal is anyone who disagrees with me is foolish. 

Because they have failed to adopt the teachings of The Homosexual Christ. Hence, they are not Christian in the sense that they are destined for Hell. Adherents to The Homosexual Christ understand that modern liberalism is better for humankind than conservatism.