This is the “mark of the beast” referred to in Revelation 13:16-18. The mark is given by the second “beast” of Revelation 13 which is also identified by the number “666.” There is probably more rubbish, complete nonsense, wild speculations, mystical notions, fanciful theories and conjurings of man written about this topic than anything else in the entire Bible. Even those who don’t read or believe the Bible seem to know what this mark is, and they are happy to tell you all about it – and it’s always wrong of course. The wildly popular (among both heathens and Christians) teachings and musings are that this mark will be a chip implant, tattoo or barcode on your forehead or hand; these are complete nonsense. This brings up a good point, which shouldn’t even have to be said, but seems necessary: do not get your Christian doctrine and Bible interpretation from secular sources! You’re in for a world of trouble and deception if you do so, and yet I see it happening all the time.
First let’s talk about the symbolism and meaning of this passage; only after this is established can we then talk about the possible fulfillments (near and far) of this mark and discuss its applicability to us today.
When you accept Christ, you are born-again of the Holy Spirit who resides in you; this is how you abide in Christ and He in you. Scripture refers to this as being “sealed” with the Holy Spirit. It is symbolically and figuratively described as having a “mark” placed on your forehead, and this mark identifies you as being a child of God. The mark is spiritual – it is not a literal physical mark! King David writes about this as “You have anointed my head with oil” (Psalm 23:5). Revelation 7:3 states that the bond-servants of God were “sealed on their foreheads.”
In contrast, for those who reject Christ, the Bible also symbolically speaks about them as having a mark placed on their forehead (or their hand) which signifies that they are following after Satan, the devil, in mind (forehead – heart and mind) and in action/deed (on the hand – doing his deeds and the deeds of this sinful world).
The Bible also refers to this marking as those who have the name of God (Christ) written on their foreheads vs. those who have the name of the World (“BABYLON THE GREAT, THE MOTHER OF HARLOTS AND OF THE ABOMINATIONS OF THE EARTH”) written on their foreheads. The symbolism is obvious and exactly the same: followers of Christ or followers of Satan (i.e., this world/man).
Those are the only two families of people on Earth, and everyone who has ever lived will be in one or the other. Correspondingly, there are two marks; you are marked either as:
- Belonging to Christ, or
- Belonging to this world (which is of Satan and those who follow him, including apostate churches and governments of man, i.e. the “beasts” in the book of Revelation)
Furthermore, these marks are constantly being given out during this gospel and church age to those who choose Christ as Lord and those who do not. So, If you are following man and the ways of the world (“for the ways of man lead to death,” Proverbs 14:12), then you have the mark of the beast (who is of Satan, and this world); if you are following Jesus, then you have the mark/anointing of the Oil of Gladness (The Holy Spirit) sealing you as a child of God. That is the symbolism described.
Let us now look at the likely specific historical fulfillments of this mark. Contrary to popular opinion today, which by and large thinks that all end-times bible prophecy (e.g. the book of Revelation) has fulfillment and application only to us who are alive now or in the future, much of the prophecy of the book (but not all) was fulfilled in the early days of the church, when they suffered extreme persecution. The hope that the book of Revelation offers would have been very necessary during the early church.
The mark likely had direct fulfillment during the early years of the church. Taking the mark meant declaring or proclaiming any man or institution of man as Lord and God (i.e., worshiping him), thereby denying the one true and living God, Jesus Christ. This worship was coerced with threats of death, persecution and economic starvation. This was likely during the extreme persecution of the early church first under Rome Pagan (i.e., Caesar) and then under Rome Papal (i.e., the Roman Catholic Church).
In the first case, if a Christian didn’t confess Caesar as Lord and God, they would be burned alive, sent to the arena to be torn apart by lions, or suffer a similar fate. Many Christians refused to take this “mark” of Caesar. Subsequently, under Rome Papal, the Roman Catholic Church was in full power, and if you didn’t confess the Pope as Lord and God, you would be excommunicated (put out of the church) and you would effectively have been cut off from all means of economic livelihood and support, for the church had an iron grip on nearly all aspects of society. Many Christians also refused the “mark” of Papacy.
I value the commentary from biblical scholars not infected with false teachings (such as Dispensational Premillennialism, Postmillennialism, Realized Eschatology, Radical Preterism, etc.), but I also weigh whether they are teaching correct doctrine in other areas as well, because as I’ve indicated, false teachings travel in packs. Reputable commentaries agree that this prophecy likely described (specifically) the persecution of early Christians by the Roman Catholic Church in the centuries after the apostolic/early church age. Note that this was coincident with the rise of Roman Catholicism (the great apostasy mentioned in 2 Thessalonians 2, the man of sin, the “lawless one,” i.e. the Pope).
On the second beast of Revelation 13, Matthew Henry writes: 
Those who think the first beast signifies Rome pagan by this second beast would understand Rome papal, which promotes idolatry and tyranny, but in a more soft and lamb-like manner: those that understand the first beast of the secular power of the papacy take the second to intend its spiritual and ecclesiastical powers, which act under the disguise of religion and charity to the souls of men. Here observe,
- The form and shape of this second beast: He had two horns like a lamb, but a mouth that spoke like the dragon. All agree that this must be some great impostor, who, under a pretence of religion, shall deceive the souls of men. The papists would have it to be Apollonius Tyranaeus; but Dr. More has rejected that opinion, and fixes it upon the ecclesiastical powers of the papacy. The pope shows the horns of a lamb, pretends to be the vicar of Christ upon earth, and so to be vested with his power and authority; but his speech betrays him, for he gives forth those false doctrines and cruel decrees which show him to belong to the dragon, and not to the Lamb.
- The power which he exercises: All the power of the former beast (Rev 13:12); he promotes the same interest, pursues the same design in substance, which is, to draw men off from worshipping the true God to worshipping those who by nature are no gods, and subject the souls and consciences of men to the will and authority of men, in opposition to the will of God. This design is promoted by the popery as well as by paganism, and by the crafty arts of popery as well as by the secular arm, both serving the interests of the devil, though in a different manner.
III. The methods by which this second beast carried on his interests and designs; they are of three sorts: – 1. Lying wonders, pretended miracles, by which they should be deceived, and prevailed with to worship the former beast in this new image or shape that was now made for him; they would pretend to bring down fire from heaven, as Elias did, and God sometimes permits his enemies, as he did the magicians of Egypt, to do things that seem very wonderful, and by which unwary persons may be deluded. It is well known that the papal kingdom has been long supported by pretended miracles.
On the “buying and selling” restriction, he writes:
- Excommunications, anathemas, severe censures, by which they pretend to cut men off from Christ, and cast them into the power of the devil, but do indeed deliver them over to the secular power, that they may be put to death; and thus, notwithstanding their vile hypocrisy, they are justly charged with killing those whom they cannot corrupt.
- By disfranchisement, allowing none to enjoy natural, civil, or municipal rights, who will not worship that papal beast, that is, the image of the pagan beast. It is made a qualification for buying and selling the rights of nature, as well as for places of profit and trust, that they have the mark of the beast in their forehead and in their right hand, and that they have the name of the beast and the number of his name. It is probable that the mark, the name, and the number of the beast, may all signify the same thing – that they make an open profession of their subjection and obedience to the papacy, which is receiving the mark in their forehead, and that they oblige themselves to use all their interest, power, and endeavour, to promote the papal authority, which is receiving the mark in their right hands. We are told that pope Martin V. in his bull, added to the council of Constance, prohibits Roman Catholics from suffering any heretics to dwell in their countries, or to make any bargains, use any trades, or bear any civil offices, which is a very clear interpretation of this prophecy.
In summary, the buying and selling restriction likely had an exact literal fulfillment under either the Rome Pagan or Rome Papal persecution of Christians in the early Church. However, this doesn’t change its application, meaning and purpose to us today, which is: if someone asks you to worship any man or idol or any institution of man instead of Christ (or they ask you to deny Christ), simply say no, even in matters of life and death through persecution! You’ll therefore never have to worry about this “mark of the beast.” In effect, if you are worshiping the things of man and this world, you already have the mark of the beast. If you are worshiping Christ in spirit and in truth, you do not have the mark of the beast.
And a final note is warranted. Bible prophecies can have both a near and a far fulfillment. So, while this prophecy was likely fulfilled in the persecution of the early church under Rome Pagan (Caesar) and/or Rome Papal (Roman Catholic Church), Satan (working through the men who choose to follow him) loves to mimic/imitate what is written in Scripture, so there may once again be a time when he tries to mimic what appears to be far fulfillment of this prophecy in today’s age. But be not deceived.
Also, it is wise to study church history, for one can learn much from those who have gone before us.
 Henry, Matthew. Exposition of the Old and New Testaments, London. 1706-1710/1721.