We should fear and love God so that we do not curse, swear, use satanic arts, lie, or deceive by His name, but call upon it in every trouble, pray, praise, and give thanks.
Personally, I have often found Luther’s comment about the satanic arts curious. Certainly Christians are not to engage in the occult, but isn’t that rather obvious? The “satanic arts” includes things like witchcraft, sorcery, fortune-telling, devil worship, etc. Christians are not immune to participating in these things, so perhaps Luther’s reminder is a welcome one, after all. But the satanic arts do not always appear in forms as crass as these. As one who seeks to disguise himself as an “angel of light” (2 Corinthians 11:14), Satan will often engage us with more subtle forms of his arts, the highest of which is presenting false doctrine as if it were godly.
Satan is a master of deception, and even the churches of Galatia, despite having heard St. Paul preach (Galatians 1:8), were susceptible to false doctrine. In Galatians 3:1, the apostle laments, “who has bewitched you?” Luther describes this “bewitching” as something that takes place when the devil causes us to see or hear things that aren’t really there. He writes, “Thus Satan has the uncommon ability to touch all the senses in such a way that you swear you see, hear, or feel something which you nevertheless do not see, etc.”
This bewitching, or witchcraft, can take place both on the physical and spiritual plane. In the physical realm, it can be as simple as imagining you’ve seen or heard something frightening. In the spiritual realm, it involves seeing or hearing things in Scripture that aren’t really there— false doctrine. Luther warns us to guard against this spiritual witchcraft, where the devil
works internally, with plausible opinions and ideas about doctrine, by which, as I have said, he so dements the hearts of men that they would swear that their most vain and wicked dreams are the most certain truth.
It should be noted, first of all, that Luther describes this false doctrine as “plausible opinions”, which people would “swear” are “the most certain truth.” That is to say, they seem to be perfectly reasonable teachings to the rational mind. Therefore, we must constantly be on our guard against pious sounding opinions which in fact contract the Word of God.
Mostly recently, Pope Francis has issued such a “pious sounding opinion” in which he asserted that “the mercy of God has no limits if one turns to him with a sincere and contrite heart; the question for one who doesn’t believe in God lies in obeying one’s conscience.” According to the pope, you do not need to believe in God, let alone Jesus, to be saved. All that is necessary is to “obey one’s conscience.”
The Catechism of the Catholic Church affirms this teaching when it says that those
who through no fault of their own, do not know the Gospel of Christ or his Church, but who nevertheless seek God with a sincere heart, and, moved by grace, try in their actions to do his will as they know it through the dictates of their conscience- those too may achieve eternal salvation.
The idea that salvation exists for those who haven’t heard the Gospel is pleasing enough to the rational mind. But this teaching is problematic because it contracts Scripture, which asserts that Jesus alone is the way to the Father, apart from Whom there is no salvation; that our works count for nothing before God, and if they did, then Christ died for nothing (John 14:6, Acts 4:12, Romans 3:20, Galatians 2:21).
One way Satan has gotten us to lower our defenses against false doctrine is by shifting the way we speak of it. No longer do we commonly refer to those who teach false doctrine as being “bewitched” (Gal 3:1), or practitioners of the satanic arts. Instead, we have adopted language that puts false doctrine on equal footing as the truth of the Gospel. What St. Paul and Luther called witchcraft, we call “interpretations.” Such language may seem at first to be neutral, as if to refuse to make a judgment of the truth or error of a teaching. But in fact it does make a judgment, one which gives equal legitimacy to all views. The doctrine of the real presence is seen as just another “interpretation” of the Words of Institution, alongside the (equally valid) symbolic “interpretation.” To give the impression that false doctrine is a mere interpretation rather than witchcraft or the satanic arts grows out of a concern to avoid offending people at all costs, even if it means offending God.
To make false doctrine sound godly is the highest of the Satanic arts. Satan will be satisfied where a crass presentation of his doctrine does the trick, but where this proves ineffective, he will not give up. He is a master of the half-truth, and even of the mostly-true. He will preserve as much of the truth as necessary so as to make his teaching sound attractive, even godly. But even a slight impurity is enough to render a doctrine lethal. A little leaven leavens the whole lump (1 Corinthians 5:6). If we are to guard against the satanic art of doctrinal impurity, we must diligently apply ourselves to the proper distinction between Law and Gospel, the highest art for the Christian. Becoming skilled in this art is the best way to guard against the satanic arts and to hallow God’s name. For God’s name is hallowed “when the Word of God is taught in its truth and purity, and we, as the children of God, also lead holy lives according to it.” May our dear Father in heaven help us to do this.
 cf. the American Edition of Luther’s Lectures on Galatians (1535), p. 191.
 Ibid., 192.
 Catechism of the Catholic Church, paragraph 847, citing Pope Paul VI’s Lumen Gentium.
 Luther, Small Catechism, explanation of the first petition.