What is very sad about folks who want to shut down authority is that they seem oblivious to the fact that such a task is impossible. The reformed principle of sola scripture contends that Scripture must interpret Scripture and that Scripture is by nature self-attesting. All other approaches to Scripture place man on the bench and the Word of God in the dock. In other words, we have disjunctive syllogism. Either Man or God is the judge. The elevation of any interpretive paradigm that sits in judgment of God’s word is hopeless subjective. If man is the measure, which man? That is the point! Those who argue in this way, also have essentials in mind as well. Otherwise, Christianity is such a free-for-all that it ceases to exist. That there was excommunication in the ancient Church over doctrinal and moral failure is indisputable. This and this alone is PRROF enough to demonstrate that the idea of essentials is rooted in biblical Christianity.
Chyrl is correct. The Trininty and divinity of Christ have been, from the beginnings of the church, required confessions for continuation in the Christian group. One the Church had established herself, she immediately began dealing with the more developed view of the triune God. Once she settled this matter, all opponents were dealt with harshly if they refused to recant the heresy. Excommunication is the biblical principle for those who deny the fundamentals of the faith. I do not say this to be offensive in any way. I say it because it is historically undeniable, and also because it is clearly what the Scriptures instruct.