Warsaw — Poland's ''battle of the crosses'' will not go away. The Communist authorities have tried to play it down, and the Roman Catholic Church has sought to avoid any head-on clash. But the controversy took a new turn last weekend when the Catholic bishops again upheld the ''right'' of Catholic parents to have the cross displayed in places where their children are educated.
The bishops' statement was contained in a pastoral letter for reading in all of the country's cathedrals and 30,000 parish churches Sunday.
Only a few days before, it had seemed the issue was being cooled when the authorities reopened the agricultural college near the rural town of Garwolin. The students began protests March 7 over the removal of crucifixes from their classrooms. The threat of an ''occupation'' strike prompted the school's closure , and it seemed the authorities had intended to keep the school closed until the end of the current term.
Ostensibly, it was reopened to pupils who - together with their parents - signed a pledge acknowledging the secular character of the school in common with all state schools. But scores of other pupils who had not made such a declaration, but still presented themselves for classes, were not denied entry.
By making their statement in the form of a pastoral letter, the bishops ensured that their message would be made known directly to the Catholic faithful. The church claims more than 90 percent of Poles are Catholic.
It was a firm renewal of the church's claim to have crucifixes in the schools. But, in the view of the best-informed observers here, the letter does not signal a church move to broaden the issue.
The real significance of the bishops' repeated stand may be seen as confirmation that - though the government discounts such a suggestion - there is some definite deterioration in the climate of church-state relations. Moreover, it implies that, with a certain ''fundamentalist'' or hard-line element on each side, the crucifix issue can only prolong that deterioration.
The saving factor, however, is that both the church and the government see the issue as a potential ''minefield.'' Neither side will wish to tread beyond continued affirmation of their respective positions. But this in itself will not bring accommodation nearer.
A local bishop, Jan Mazur, who, at the outset, characterized the incident as ''a war on the cross,'' last week began a Lenten fast on bread and water which he said he would maintain until crosses are restored to their original places.
Almost half the school's 600 pupils board at the school, since it is one of the principal Polish agricultural training centers and draws pupils from all over the country. It was established by reporters last week that personal crucifixes adorning the walls in the boarders' sleeping quarters had not been removed.
The authorities see this as confirmation of their assertion of respect for religious beliefs as a matter of personal conviction and right. In their pronouncements on the issue, they invoke the constitutional separation of church and state and hence the exclusion of religious emblems within the schools.
The bishops' pastoral letter called on the authorities to allow the cross its ''proper place'' in Polish life. It too invoked Polish law as the guarantee of parental right to have their children brought up in the Christian spirit.
But officials will obviously hold that such a guarantee applies to Christian teaching through the churches and in places of worship, but not in the state schools. They also argue that this is in fact in no way impeded in practice.
The issue has not yet generated tension approaching the kind that, from time to time since the 1950s, led to icy standoffs lasting for years between Catholic Church and Marxist government. Today the relationship is on considerably stronger and more realistic foundations. Recently the Polish church has seen a remarkable extension of church-building, a proliferation of publications (albeit limited by paper shortage and censorship), and much greater religious tolerance than elsewhere in Eastern Europe.
Yet both church and state appear momentarily to be digging in on positions that will make inevitable compromise difficult without gestures on each side.
(In Gdansk, Solidarity founder Lech Walesa said Sunday the authorities would not dare try to take crosses down in factories, and that their removal from schools was ''an attempt to hit at the weak,'' Reuters reports.)
Moreover, the present sensitiveness seems reflected in a comment by the primate in which he refuted a West German magazine's suggestion that the church is seeking to create a Catholic party in Poland.
The article was reprinted March 31 by the once ''liberal'' but now largely pro-government Polish weekly Polityka.
Asked about his concern for ''national conciliation,'' Jozef Cardinal Glemp said this did not mean conciliation through ''mutual concessions'' by church and state.
At ''the present stage of our moral and social crisis,'' he went on, ''it makes more sense to speak of the necessity of coexistence amid contradictions.''
This was the fundamental truth of the church's commitment, he said, and it was a ''naive belief'' to see the church as contriving to gain political influence.
The contradictions are undoubtedly there, whether or not coexistence means compromise or concessions. And each side is considering concessions.
If the church takes a conciliatory approach, its gains might be greater than if it pursues a confrontational approach over the crosses. To dispassionate observers here, the crucifix issue is one the church cannot hope to win.