There are Protestants who preface major decisions that they make with some variation or other upon this theme: “God told me…” (I don’t mean to skewer Protestants particularly in this post, though. I’m sure that there must be Catholics who do the same thing—as we shall see—but I haven’t come across them). When they say this, they rarely have in mind some passage or other from the Bible. Rather, what they have in mind is a belief that God has given them directions about their lives in some undefined extra-biblical way: maybe by means of some sign or other, or maybe by actually speaking to them. I have personally known someone who divorced her spouse on those grounds (!).
The problem with such communications—granting that someone communicated something—is that by themselves there is no way to know where they actually come from. This is a portion of what St John of the Cross says about this subject:
I am appalled at what happens in these days — namely, when some soul with the very smallest experience of meditation, if it be conscious of certain locutions of this kind in some state of recollection, at once christens them all as coming from God, and assumes that this is the case, saying: ‘God said to me . . ,’; ‘God answered me . . ,’; whereas it is not so at all, but, as we have said, it is for the most part they who are saying these things to themselves.
5. And, over and above this, the desire which people have for locutions, and the pleasure which comes to their spirits from them, lead them to make answer to themselves and then to think that it is God Who is answering them and speaking to them. They therefore commit great blunders unless they impose a strict restraint upon themselves, and unless their director obliges them to abstain from these kinds of reflection. For they are apt to gain from them mere nonsensical talk and impurity of soul rather than humility and mortification of spirit, if they think, ‘This was indeed a great thing’ and ‘God was speaking’; whereas it will have been little more than nothing, or nothing at all, or less than nothing. For, if humility and charity be not engendered by such experiences, and mortification and holy simplicity and silence, etc., what can be the value of them? I say, then, that these things may hinder the soul greatly in its progress to Divine union because, if it pay heed to them, it is led far astray from the abyss of faith, where the understanding must remain in darkness, and must journey in darkness, by love and in faith, and not by much reasoning. [Ascent of Mt Carmel, II, xxix, 4-5; emphasis added]
Later St John points out that Satan might likewise “speak” to people and thereby deceive them if they take such speech to be God’s. The point is that there is grave hazard in taking such locutions (to use the Saint’s/translator’s word) as divine without serious testing. But how should they be tested? The answer should be obvious: they must be tested against the truths of the Faith. It is impossible for God to say things to us that contradict what the Church teaches. Consequently if we suppose (borrowing from the previous example) that God tells us to get a divorce, we are wrong. And the same is absolutely certain in any case where “someone” tells us to do something contrary to the Faith. We’re a lot better off being content with the truth that God has already given us than clamoring after something more, as if what He has already given is insufficient. It’s not.