The Apostle Paul writes in his Letter to the Romans about Justification, Baptism and the ethical requirements of Christianity.
In the development of his Letter he makes an analysis of sin, that is to say, there are certain actions that, although they do not affect the neighbor, that is, they do not harm him, because they are reprehensible like vices, they are sin. Thence the affirmation: Whatsoever is not from faith is sin. Romans 14:23, or expressed in another way as the old saying goes: "what is worth is the intention".
The apostle gives the example in the Letter of those who eat and drink in order to provoke scandal.
Certain situations raise certain questions. Discernment between good and evil is necessary in many situations. How to judge, how to discern when virtue becomes a vice?, How to discern when truth and life are oppose, where is the correct? Where is the ethics?
Often the objective facts are not enough to clarify, to discern. We need something else and that something else is the intention of the people. Good and evil, success and error are disjunctives.
What is not made in faith is sin, this is so because Christ teach us that is from the heart that comes both, the good and the evil intention: "For from within, out of the heart of men, proceed evil thoughts, adultery, fornications, murders, thefs,wickedness, deceit, lascivousness, envy, blasphemy, pride, foolishness. All these evil things come from within and defile the man" Mark 7: 21-23.
A clear example in the Bible about the importance of evaluate the intention of the people to discern, to judge correctly, is the case of King Solomon and the two prostitutes, 1 Kings 3:16. The King discovers the truth not based in the evidence but through which comes from the heart of the prostitutes.