This is how historic Protestants discern truth. This is taken from the Westminster Confession of Faith in regards to Scripture:
All which are given by inspiration of God, to be the rule of faith and life.
III. The books commonly called Apocrypha, not being of divine inspiration, are no part of the Canon of Scripture; and therefore are of no authority in the Church of God, nor to be any otherwise approved, or made use of, than other human writings.
IV. The authority of the holy Scripture, for which it ought to be believed and obeyed, dependeth not upon the testimony of any man or Church, but wholly upon God (who is truth itself), the Author thereof; and therefore it is to be received, because it is the Word of God.
V. We may be moved and induced by the testimony of the Church to an high and reverent esteem of the holy Scripture; and the heavenliness of the matter, the efficacy of the doctrine, the majesty of the style, the consent of all the parts, the scope of the whole (which is to give all glory to God), the full discovery it makes of the only way of man’s salvation, the many other incomparable excellencies, and the entire perfection thereof, are arguments whereby it doth abundantly evidence itself to be the Word of God; yet, notwithstanding, our full persuasion and assurance of the infallible truth and divine authority thereof, is from the inward work of the Holy Spirit, bearing witness by and with the Word in our hearts.
VI. The whole counsel of God, concerning all things necessary for his own glory, man’s salvation, faith, and life, is either expressly set down in Scripture, or by good and necessary consequence may be deduced from Scripture: unto which nothing at any time is to be added, whether by new revelations of the Spirit, or traditions of men. Nevertheless we acknowledge the inward illumination of the Spirit of God to be necessary for the saving understanding of such things as are revealed in the Word; and that there are some circumstances concerning the worship of God, and the government of the Church, common to human actions and societies, which are to be ordered by the light of nature and Christian prudence, according to the general rules of the Word, which are always to be observed.
VII. All things in Scripture are not alike plain in themselves, nor alike clear unto all; yet those things which are necessary to be known, believed, and observed, for salvation, are so clearly propounded and opened in some place of Scripture or other, that not only the learned, but the unlearned, in a due use of the ordinary means, may attain unto a sufficient understanding of them.
VIII. The Old Testament in Hebrew (which was the native language of the people of God of old), and the New Testament in Greek (which at the time of the writing of it was most generally known to the nations), being immediately inspired by God, and by his singular care and providence kept pure in all ages, are therefore authentical; so as in all controversies of religion the Church is finally to appeal unto them. But because these original tongues are not known to all the people of God who have right unto, and interest in, the Scriptures, and are commanded, in the fear of God, to read and search them, therefore they are to be translated into the vulgar language of every nation unto which they come, that the Word of God dwelling plentifully in all, they may worship him in an acceptable manner, and, through patience and comfort of the Scriptures, may have hope.
IX. The infallible rule of interpretation of Scripture, is the Scripture itself; and therefore, when there is a question about the true and full sense of any scripture (which is not manifold, but one), it may be searched and known by other places that speak more clearly.
X. The Supreme Judge, by which all controversies of religion are to be determined, and all decrees of councils, opinions of ancient writers, doctrines of men, and private spirits, are to be examined, and in whose sentence we are to rest, can be no other but the Holy Spirit speaking in the Scripture.
