At the international airport here, there is a poster showing a confident Lebanese soldier breaking chains of bondage wound around him while he steps with both feet on a long snake writhing on the ground. At the bottom are the words, "The Dawn of Salvation."

A departing visitor asked a Lebanese airport employe what the snake represented. "All the evil forces alive and working against us in this country," he replied. "But you'll notice," he added with a smile, "the soldier's foot is still not on the head of the snake."

Four months after President Amin Gemayel took office in a wave of short-lived optimism stirred by the reunification of Christian East and Moslem West Beirut, the forces of evil indeed still seem very much alive in this hapless land of eternal conflict.

Fighting between Christian and Druze militiamen in the mountainous Chouf region has now reached the outskirts of the capital, with both sides using increasingly heavy artillery. Pro- and anti-Syrian Moslem factions are at war in the northern port of Tripoli. Iranian fundamentalists have all but taken over in Baalbek in the east, and the Israelis are busy setting up a bewildering array of militias across the south.

The familiar pattern in which political and religious chieftains gather to discuss local clashes, issue orders for a cease-fire and then go home to watch it break down the next day has reemerged as the norm. Despite innumerable palavers among warring factions, no underlying political accord has been struck in either the Chouf or Tripoli.

Where a few months ago there was heady talk of "the new Lebanon" and "the second republic," Lebanese today debate instead the likelihood of an Israeli-Syrian "condominium" over the country or of separate Druze and Christian "ministates," joking about "the new Lebanons."

They joke, too, about their new president and his dogged efforts to put together a strong central government and Army, some noting the irony that a Christian rules only over Moslem West Beirut. The powerful Christian militia, the Lebanese Forces, dominates the eastern half of the city, and Gemayel's tiny realm is dubbed "the Duchy of Hamra Street" after its main boulevard.

"Amin is a good president because he is a weak president," one Christian editor of a major local newspaper remarked wryly. "Who really wants a strong government in Lebanon?"

But this dark humor barely conceals the real fears lurking in the minds of many Lebanese that their country, far from being on the verge of emergence as a "new Lebanon," is again on the slippery slope heading toward renewed chaos and civil war.

As usual, the Lebanese blame outsiders for all their new woes, even as they look to them once again for salvation from their own sectarian strife. Before, it was all the fault of the Palestinians. Now they are gone, so the Israelis, Syrians or Americans are taking the blame--with some justification in each case.

By all accounts, one of the main underlying causes of the worsening situation is the U.S. failure to get a quick withdrawal of Israeli, Syrian and Palestinian troops from the country. This has made it impossible for Gemayel to extend central government rule beyond the capital's city limits and has left the rest of the country at the mercy of the outside powers.

Moslem West Beirut, disarmed and deceptively peaceful, is increasingly fearful. There has been a spate of recent reports about the Lebanese Forces sending in armed men, kidnaping people, stockpiling arms and opening underground cells.

The belief is that the Phalangist Party, which dominates the Lebanese Forces, is getting ready to push back into areas inside West Beirut where it once held sway before Moslem militias drove them out in the 1975-76 civil war.

In early December the Phalangists tried to reopen an office in Museitbeh, near the headquarters of Druze leader Walid Jumblatt's Socialist Progressive Party.

"The Moslems in Beirut are very frightened and concerned. They have been disarmed while the Lebanese Forces are still intact and acquiring additional strength," said a Moslem editor who asked not to be named. "They feel the Lebanese Forces are already getting into West Beirut."

"I think we are going to have another civil war," he added grimly.

The reaction among the Moslems is to get ready for the next round. Leftist groups belonging to the old National Movement led by Jumblatt are now reviving and busy smuggling their own arms and men into the city.

They also are reestablishing the underground infrastructures that they had before the Israelis and then the Lebanese Army combed the streets and homes of West Beirut last September.

A sign of the times, in the Moslem view at least, came on Dec. 27 when Moslems poured into the streets of West Beirut on the occasion of the prophet Mohammed's birthday. Banners draped across the streets said, "Moslems are not just a community. They are the spirit of Lebanon." Cardboard imitations of the Kaaba, the Moslem holy of holies in Mecca, hung from lampposts.

"This never happened except before the troubles started in 1958," remarked the Moslem editor, referring to an earlier time of difficulties when U.S. Marines were last sent to Lebanon.

Moslem fears for the future really began last September when the Army, in its first show of muscle-flexing and authority after eight years, moved into West Beirut and carried out a house-to-house search for arms and illegal aliens. Moslem leaders did not protest until it became clear that the Army had no intention of treating Christian East Beirut to the same intensive search or of disarming the Lebanese Forces.

Since then, the Army's security branch, the Deuxieme Bureau, steadily has worked to uproot remaining underground cells of the Palestine Liberation Organization and leftist Moslem militia groups, combing the Palestinian refugee camps for persons whose names often are provided by the Israeli or Lebanese Forces' intelligence services.

This has badly shaken the Moslems' confidence in the supposed neutrality of the national Army, whose new commander, Ibrahim Tannous, was a close friend of the slain Lebanese Forces leader and brother of the president, Bashir Gemayel.

Fadi Frem, the new Lebanese Forces commander, set forth the rightist Christian view of the "new Lebanon" at celebrations Nov. 28 marking the 46th anniversary of the Phalangist Party.

"Let us not return to the no-win, no-lose formula," he said. "This time there is a victor and a vanquished. The victor is the Lebanese way of thinking, and the vanquished are imported ideas."

While political parties upholding "the Lebanese idea" are the winners, he declared, "we can consider vanquished each party that adhered to, or supported, or gave local cover to imported ideas."

It is this view of Lebanese politics that has Moslems convinced that the Lebanese Forces intends to impose its will by force of arms and must be resisted in a similar fashion if the "Moslem spirit" is to breathe at all in the new Christian-dominated Lebanon.

Some Lebanese Forces leaders are becoming alarmed at the sectarian turn that events are taking, even while insisting that their militiamen have the right to go anywhere in Lebanon where there is a Christian to protect.

As they perceive it, Lebanon's presumed "vanquished," notably the socialists and communists, have worked out a plan with Syrian, Palestinian and Soviet backing to destabilize first the Chouf and then the entire country. The fighting in the Chouf, according to Phalangist leader Pierre Gemayel, is the fault of "international communism" and really a "ricochet war" of the larger U.S.-Soviet struggle for dominance in the Middle East.

"The manipulation [of the Chouf fighting] by the communists is becoming clearer and clearer," said Lebanese Forces commander Frem in an interview. "Their plan is to use the party of Mr. Jumblatt as cover and in the second place to give the perception that it is a confessional conflict between Druze and Christians.

"In a sense they have succeeded to give this perception to the Druze themselves, telling them the Christians want to throw them out of the country, especially after all the propaganda that was made about us in Sabra and Shatila," he said, referring to the involvement of Lebanese Forces militiamen in the massacre inside Beirut's Palestinian refugee camps.

Both Moslem and Christian leaders seem to agree that the conflict--whether political, religious or both--is now coming close to engulfing the capital itself, which so far has been treated by both sides as a kind of "open city" free of warfare.

Last week, Druze militiamen shelled within 500 yards of the presidential palace in the Beirut suburb of Baabda, badly shaking President Gemayel, according to one confidant. The incident showed that Jumblatt's militia has obtained new Soviet-made rockets to combat the Lebanese Forces' long-range 155 mm artillery and is ready to escalate the fighting on the fringes of the capital.

"The situation in the Chouf," remarked the Moslem editor, "has created a psychological atmosphere. Now, we have gone back to the mentality of retrenchment. . . .How are we ever going to have a united Lebanon and peace and quiet?"