First of all it is necessary to contextualize the established church.
At the time of Jesus the " church" was the sanhedrin which were waiting a king and their cultural beliefs were more religious that other thing.
If this the context the people that didn't follow their ( Sanhedrin) rules were considered as protestants.
But after Jesus time the any denomination which protest against the established. Originally the established church was the catholic church.
The protestant movement ( Reform around 1500) is a big branch of christians which protested against the established chuch.