Demographers have described Chicago as a ''hyper-segregated'' city where blacks and whites are less likely to live on the same block -- or encounter each other on the sidewalk -- than almost anywhere else in the country. Chicago's Roman Catholic archbishop, Cardinal Francis George, confronted this problem in a powerful pastoral letter last spring. He admonished priests, nuns and lay people who had refused ''to welcome even Catholic African Americans into parishes and schools.''

The letter was issued last April -- just a month before Chicago, the third-largest city in the country, experienced an act of racial exclusion that seemed like something out of the distant past. St. Sabina, a black Catholic parish, was denied membership in the Southside Catholic Conference, an athletic league made up of 21 white Catholic parishes. The league initially rejected St. Sabina on the grounds that its neighborhood, which is within walking distance of some other league members, was unsafe for whites. The black parish was eventually allowed to join, but withdrew abruptly last week citing what its fiery pastor, the Rev. Michael Pfleger, has described as ''racist'' treatment. His rhetoric angered the archdiocese, which already viewed Father Pfleger as an inflammatory figure.

This year, St. Sabina says, its team was required to play some away games at ''neutral'' sites because some schools did not want its students on their premises. Tension heightened when the league invoked questionable rules that disqualified some St. Sabina players. When St. Sabina accused a boy from another school of using a racial slur during a game, the league failed to follow its own mediation procedures, which require a meeting between the parents of the children involved. Frustrated and fearful, the St. Sabina parents voted unanimously to leave the league.

Chicago's history of segregation and racial hostility has given this event a symbolic importance that goes well beyond sports. Cardinal George, Father Pfleger and the South Side Catholic Conference need to cool the rhetoric and do their best to restore integration to the parish league. If white Catholics and black Catholics cannot make peace long enough for their children to play together, the prospects for reconciliation will seem dimmer for us all.