On liberalism

For the purpose of this post I'll assume liberalism for the modern Protestant Christian is:

a movement in modern Protestantism emphasizing intellectual liberty and the spiritual and ethical content of Christianity

Source

It's interesting the definition of liberalism assumes "intellectual liberty."  What sort of intellectual liberty should Christians be willing to accept?  Should it be liberation from certain basic tenants of Christianity?  A lot of liberals tend to say they follow Jesus.  Okay, and where are they getting their information about Jesus from?  I mean, surely there some ramifications in breaking away from Tradition and Scripture; indeed, even liberals need to have some sort of foundational beginning.  I guess, I want to know where the starting point for the liberal begins.  Can they even have fundamental premises to adhere to?