Here’s an interesting quote from Jonathan Edwards in his sermon “A Divine and Supernatural Light” where he describes how believers possess certainty of the truth of biblical doctrine.
A true sense of the divine excellency of the things of God’s Word doth more directly and immediately convince of the truth of them; and that because the excellency of these things is so superlative. There is a beauty in them that is so divine and godlike, that is greatly and evidently distinguishing of them from things merely human, or that men are the inventors and authors of; a glory that is so high and great, that when clearly seen, commands assent to their divinity, and reality. When there is an actual and lively discovery of this beauty and excellency, it won’t allow of any such thought as that it is an human work, or the fruit of men’s invention. This evidence, that they, that are spiritually enlightened, have of the truth of the things of religion, is a kind of intuitive and immediate evidence. They believe the doctrines of God’s Word to be divine, because they see divinity in them, i.e. they see a divine, and transcendent, and most evidently distinguishing glory in them; such a glory as, if clearly seen, don’t leave room to doubt of their being of God, and not of men.
Alvin Plantinga cites descriptions like these from Edwards (e.g., Warranted Christian Belief, 100-101) in support of his extended A/C (Aquinas/Calvin) model of warranted Christian belief, in which the believer acquires knowledge (both true and warranted belief) of “the great things of the gospel”– a phrase borrowed from Edwards — by the internal testimony or instigation of the Holy Spirit.
The believers described above by Edwards could be understood to be those on Plantinga’s model who have been enlightened by the Holy Spirit to believe in the divine origin and truth of core biblical teachings. They possess “a kind of intuitive and immediate evidence” and “see divinity” in the “things of God’s Word.
Plantinga’s Reformed Epistemology makes a lot of sense to me, and he and Edwards seem to be in agreement on at least this point.