MAYBE IT'S that weird red mark on Mikhail Gorbachev's forehead. Maybe it's conservative disappointment that Ronald Reagan has gone to Moscow. But for whatever reason, there is a small but vocal group of fundamentalist Christians who are prepared to argue that the Soviet general secretary is the Antichrist, the Devil's agent on Earth. They don't simply mean that Gorbachev is an evil man, or that he represents an evil system. No. They mean that he is the tool of the Devil. The Antichrist. Mr. 666 himself.

"The evidence is overwhelming that Gorbachev is the Antichrist," says Robert W. Faid, a 59-year-old former engineering supervisor who holds a master's degree in theology from Coatesville Bible College and is author of "A Scientific Approach to Christianity." He argues in a new book, "Gorbachev! Has the Real Antichrist Come?," that the Soviet leader fulfills virtually all the biblical prophecies about the Antichrist.

To Faid, last week's summit meeting in Moscow was a tragedy: "I'm sure that President Reagan has no idea that who he's talking to is, as the evidence indicates, the Antichrist."

Take the matter of that birthmark on Gorbachev's forehead. To Faid and those who share his views, that's not just an ordinary birthmark. It's The Mark of Satan.

"When I look at the top of Gorbachev's head, I see a red dragon and over the right eye, there's a tail that hangs, representing stars," says Faid. He explains that St. John, in Revelations: 12:3-4, portrays Satan in similar terms, as a "great red dragon . . . and his tail drew the third part of the stars of heaven, and did cast them to the earth

. . . " Thus, says Faid, "If Gorbachev is truly the Antichrist, Satan branded him in his mother's womb."

The Antichrist, in New Testament lore, is the Satanic dictator who will plunge the world into misery and war before Jesus Christ returns to save the faithful. There have been previous candidates nominated for this post by fundamentalist Christians -- mostly notably Henry Kissinger (personally, I think he's too short for the job). But none, in the view of Faid and some fellow believers, has so perfectly matched the clues outlined in Revelations and elsewhere. Among the signs: the numerical value of his name which is a multiple of the dread 666, if you use "theomatic" theory and his dominion over what Revelations calls the "ten crowns," which Faid says are actually the Soviet bloc nations, the Baltic states and Afghanistan.

Naturally, this news will be rather disappointing to those who have placed their hopes on summitry and detente. Even the ratifying of intermediate-range nuclear forces (INF) treaty and the prospect of a strategic arms reduction (START) treaty won't allow us to avoid the dark fate that awaits us when Gorbachev and his atheistic henchmen conquer the world, Faid notes. As he points out in his book, the Russian word for peace -- pronounced "mir" -- also means "world."

"How much clearer must it be?" Faid writes. "When Gorbachev says, 'I want peace,' he is really saying, 'I want the world.

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If Gorbachev is indeed the Antichrist, of course, it could change the landscape of American politics. For one thing it will make it very hard for Reagan and any future president to sell to the Senate any arms agreements with him. Democrats, nervous about seeming to be weak on defense, might back away from any type of agreement with the Devil's chief represenative on earth.

Even the traditionally liberal residents of Washington, D.C. might vote against the Democrats if the party sought to make too many concessions to the Antichrist. It could even become the sort of election-year issue that might offer George Bush yet another opportunity to take a position independent of the president. The headlines would read: BUSH TO SATAN: NO DEALS.

The Gorbachev-as-Antichrist thesis is the latest example of a centuries-old search among some Christians for the Antichrist. Martin Marty, a theology professor at the University of Chicago, argues that the long-standing effort to identify the Antichrist is akin to "Christian astrology . . . you can make anything come our right." He says that the fundamentalists' concern over Gorbachev actually stems from another cause: "Fundamentalists who counted on Reagan to be absolutely unbending in his opposition to Communism are confused. They feel there's a Satanic conspiracy behind the Administration's relative friendliness to the Soviets."

But Faid says he bases his conclusions on what he sees as the cumulative effect of 14 of 16 Antichrist indicators in Revelations applying only to Gorbachev. (The two prophecies that don't apply -- the healing of a "deadly wound" on one of the beast's heads -- haven't happened yet; Faid believes they're metaphors for the crushing of an upcoming revolt in Poland.) How strong is Faid's evidence? Decide for yourself. He uses a book "Theomatics" co-authored by former basketball star Jerry Lucas to show how in Greek, Hebrew and Russian, the letters in Mikhail S. Gorbachev's name add up to multiples of "666." (Revelations, 13:18: "Let him that hath understanding count the number of the beast . . . his number is Six hundred threescore and six."

Still not convinced? Well, Faid has over a dozen other selections from the Bible to prove his point. In Revelations 13:1, this key passage appears: "And I . . . saw a beast rise up out of the sea . . . " One reason, he argues, that the "sea" is really the Soviet Union is that when Gorbachev was named the leader of the Soviet Union, the country's population was 276 million -- and 276 is Satan's number, according to fundamentalist number buffs like Faid.

Here's how Faid explains Gorbachev's swift rise in the Communist Party hierarchy: "Who is responsible for all this? There can be only one answer! Satan was responsible." All the cumulative evidence, Faid calculates, means that the odds that Gorbachev is actually the Antichrist are more than "seven hundred and ten quadrillion" to one (to be exact: 710,609,175,188,282,100 to 1) -- a figure he arrived at by calculating the probability of one man meeting all of the Biblical requirements for the Antichrist.

Even more disturbing, he says, are the horrors the Antichrist -- i.e., Gorbachev -- will inflict on us once he conquers the world. Aong them: the "mark of the beast" tatooed on the hand or forehead of all persons who wish to buy or sell goods, including food. Faid predicts that the mark itself could be "the series of bars utilized in the Univeral Products Code already in place in most supermarkets." Police would use portable, hand-held scanner wands to enforce conformity to the Antichrist's rules. This Satan-meets-high-tech scenario could ultimately force people to choose between eating now or facing eternal damnation later, he says. I get the willies just thinking about it.

Art Levine is a Washington writer.