Vienna — Even as Vice-President George Bush was in Bucharest last month warning the Romanians to improve their human rights performance if American economic support is to continue:
* The skipper and two crew members, both family men, of a Romanian commercial vessel were sitting out five- to seven-year sentences (passed two years ago) for bringing ''illegal'' Christian literature into the country.
* A priest in an outspoken ''Army of the Lord'' movement in the otherwise docile Romanian Orthodox Church, Father George Calciu-Dumitreasa, was serving a 10-year sentence imposed in 1979 for his support of a free trade union. (He had already spent almost half his 55 years in jail.)
* Police surveillance and harassment continued for many recently released Baptist ministers and lay workers sentenced in 1980 and '81 for distributing Bibles and other religious materials.
Compared with other East European countries, dissent has surfaced rarely in Romania, principally because the regime of President Nicolae Ceausescu is the most effectively repressive - and militantly antireligious - in the bloc.
But in the 1970s the Czechoslovak human rights group Charter 77 and the stirring labor movement in Poland, plus the example of ''liberalization'' in Hungary, encouraged several Romanian groups to challenge their rulers' intolerance of and disregard for workers' rights.
The efforts were short-lived. In 1978, an independent Christian Committee to Defend Freedoms of Religion and Conscience began monitoring cases of overt persecution and sought to put pressure on the authorities to honor constitutional guarantees. Immediately, many Baptist and Seventh-day Adventist ministers and laymen in Romania were arrested and sentenced.
A year later, the government crushed the Free Trade Union Movement of Romania , putting more than a score of the union's militants in prison or psychiatric clinics.
Except for a brief wave of literary dissent by lesser-known writers, only religious groups - mainly the Baptist Church - have continued to offer resistance.
Romania is officially an atheistic state. Over the past year a campaign against religion has intensified, amid demands - led by Mr. Ceausescu - for more effective atheistic teaching in the schools. The campaign was prompted by growing evidence that young people are being drawn to communities like the Baptist, Pentecos-talist, and Adventist churches. It is apparently the more militant preaching of these churches, compared with what is seen as the regime-accommodating National Orthodox Church, that accounts for their popularity.
All religious activity is controlled by the official Department of Cults. Only 14 of the 60 denominations that existed before World War II are recognized. Believers of the others face severe penalties if they try to hold public services. Baptist ministers who have baptized people outside their own congregations have been dismissed from their parishes for conducting illegal services.
Romania's Baptist Church, with 200,000 members, has the largest Baptist following in Eastern Europe - and faces the heaviest pressures.
Only the government may print Bibles, and it does so in very limited numbers. Importing Bibles is forbidden, and clergymen who smuggle them court drastic punishments.
Last year, 66 Baptist ministers petitioned Mr. Ceausescu for permission to print and import Bibles, to train more ministers, and to manage their own church funds, which are under government control. The Department of Cults denounced the petition as an antistate provocation. There was no formal reply.
The government hardened its position recently, demanding more emphasis on atheistic teaching from primary school to university. The move is obviously aimed at the growing impact of both the legal and the unauthorized neo-Protestant denominations - which include Baptists, Methodists, Lutherans, Hussites, Reformed Calvinists, Adventists - on young Romanians.
Earlier this year, when it was touch and go in Congress whether Romania's ''most-favored-nation'' (MFN) trading terms with the US would be renewed, the regime eased up on emigration and freed a number of churchmen detained or imprisoned since last year.
Romania was granted its favored trade status, but with a distinct signal from Washington that future renewal will depend even more on full observance of human rights.
Some Romanian exiles in the West feel the US should have taken a tougher line. ''As it is,'' remarked one, ''Ceausescu will go on making just sufficient gestures each year when MFN review comes round.''