Historically, there were three doctrines that served to define the Reformation in particular, and Protestantism in general: Sola Scriptura (Scripture alone), Sola Fide (Faith alone), and Sola Gratia (Grace alone). The key word here is alone. Without the “alone” the reformers would not have distinguished themselves from the Roman Catholic Church. The Catholic Church certainly accepted Scripture as authoritative. They also believed that man was justified by faith and saved by grace. What they didn’t agree with was the “alone” part.
So what are we actually talking about when we talk about sola scriptura?