2 Cor 3:6 – “the letter killeth, but the Spirit giveth life.” A verse that is frequently misused and misapplied to mean that we should focus on our feelings as a source of light superior to the Bible (here’s one example). To my surprise, Calvin wrote about this almost 500 years ago – wish he had had the ability to make the error go away!
Those who, rejecting Scripture, imagine that they have some unique way of getting in contact with God, are to be regarded not so much under the influence of error as of madness. For certain giddy men have lately appeared, who, while they make a great display of the superiority of the Spirit, reject all reading of the Scriptures themselves, and deride the simplicity of those who only delight in what they call the dead and deadly letter [alluding to 2 Cor 3:6, “the letter kills, but the Spirit gives life”]. But I wish they would tell me what spirit it is whose inspiration raises them to such a sublime height that they dare despise the doctrine of Scripture as poor and childish. If they answer that it is the Spirit of Christ, their confidence is exceedingly ridiculous; since they will, I presume, have to admit that the apostles and other believers in the primitive Church were not illuminated by any other Spirit.
John Calvin, Institutes I.9.1 Beveridge edition (slightly paraphrased)
In context, Paul speaks in 2 Cor 3 of the letter that kills (the Old Covenant apart from Christ) and the Spirit who gives life (the New Covenant); he is speaking of salvation, not methods for determining God’s will.
“Is the Bible the ‘letter’ that kills us? Not at all!” by Gary S. Shogren, Professor of New Testament, Seminario ESEPA, San José, Costa Rica
Open Our Eyes, Lord! 
In my experience, this verse has been used by believers who want to escape verses of Scripture that clearly conflict with immoral choices, challenges pet doctrinal positions, and even church practices.