Evangelicals, Fundamentalists and non-denominationalists often distance themselves from mainline Protestant Churches. The line between mainline and Evangelical is not often clear however. Many Southern Baptists consider themselves to be Evangelicals. But the point is that many distance themselves from the older, more organized “mainline” Protestant denominations such as Lutherans, Methodists, Presbyterians, etc., which they see as just as bad as the Catholic Church.
This is highly simplified, but for many the belief is that the corporate institution is not divine, and exists as an aid in his personal relationship to Jesus. The personal relationship with Jesus is everything, and when an organization begins to insert itself between the believer and Jesus, when it supposes to be a mediator or arbitrator between Jesus and the believer, that becomes a problem for many. To these, “Protestant” is just another term for Churches which grew too big or became to established or entrenched, and have inserted themselves artificially between the believer and Jesus.
My self proclaimed “non-denominational” friends would distance themselves from Lutheran, Presbyterian and Methodist “Protestants” as quickly as they would distance themselves from Catholics. They will quickly tell you that they are not Protestant - they shrug and say things like, “I’m not protesting anything.” You speak to these about Martin Luther or Calvin and they look at you as if you have three heads and ask you why you are talking to them about a five hundred year old dead guy. They will tell you that Luther and Calvin have nothing to do with their faith, that their faith is based on their own reading of the Bible and their own relationship with Jesus.
Though the lines are sometimes blurred, Evangelical non-denominational Christianity is truly another branch of Christianity apart from Protestantism in the eyes of many of its own.
-Tim-