Please give scriptural references which gave the Protestant Reformers this idea?
We are told by an apostle to “test everything” and hold on to what is good (1 Thessalonians 5:21). This, it should be noted, was in the context of disputes over prophecy–disputes over speech linked to God. Still, we are to test it and everything else.
If the Bible is God’s word written, it is by definition sufficient to accomplish its purpose. As we are taught in Isaiah 55:10-11:
For as the rain and the snow come down from heaven
and do not return there but water the earth,
making it bring forth and sprout,
giving seed to the sower and bread to the eater,
so shall my word be that goes out from my mouth;
it shall not return to me empty,
but it shall accomplish that which I purpose,
and shall succeed in the thing for which I sent it.
What is Scripture able to accomplish? It is “able to make you wise for salvation through faith in Christ Jesus” (2 Timothy 3:15). What is its purpose? “All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness, that the man of God may be complete, equipped for every good work” (2 Tim. 3:16-17).
So, we test everything against that which will not be found empty—testing even oral teachings we are told go back to Christ or prophecy or just simple “impressions” a Christian may receive or even someone’s preaching and even ourselves.
Now, I know Catholics say that their oral teachings that they trace from Christ through the Apostles and on down through our own very day are necessary to fully understand Scripture. They even cite the presence of tradition in the Bible. Yet, we know of those traditions because they were recorded in what became the Bible. Unless a tradition, teaching, or revelation is recorded in the Bible or even just implied in the Bible, the only source for them are fallible men, no matter how holy and spiritual they may be.
This means elements of such oral teachings could be human made tradition. Some of these traditions may be pious or at least harmless, but when held up to bind the consciences of everyone as articles of faith that must be believed, human made traditions are also capable of obscuring the word of God. As Jesus noted to the Pharisees and scribes in Matthew 15:6-9:
So for the sake of your tradition you have made void the word of God. You hypocrites! Well did Isaiah prophesy of you, when he said:
“‘This people honors me with their lips,
but their heart is far from me;
in vain do they worship me,
teaching as doctrines the commandments of men.’”
This is not to say that everything outside of the Bible must be rejected or ignored or condemned. We should just remember that “God alone is Lord of the conscience, and hath left it free from the doctrines and commandments of men” (Westminster Confession Chapter 20).
So, I have, no doubt imperfectly, attempted to explain why Protestants believe “although the church is a witness and guardian to holy Scripture, it must not decree anything contrary to Scripture, nor is it to enforce belief in anything additional to Scripture as essential to salvation” (Article 20, Thirty-Nine Articles of Religion).
What difference do you see between “a group of men in the church” and “all teachers within the church”?
A group of men would be a group of men without any qualifications other than their gender. Teachers would be those in a teaching office or function.
But if you’re asking me about my quote, I made no distinction because the “group” I was speaking of was a group of teachers. As my quote makes clear, "the church should not give any one man or group of men
authority to teach. . . " Men with authority to teach are teachers.
But, everyone should judge all teaching in the church against Scripture to see how the teaching holds up. I do not believe it is just the responsibility of the teacher (though he has greater responsibility because he is the one doing the teaching) but someone sitting in the pew would have responsibility to test what the teacher was saying.