The Russian Orthodox Church has invited Pope John Paul II to send a delegation to the Soviet Union for celebrations of the 1,000th anniversary of Christianity in Russia and the Ukraine, Vatican officials said Tuesday. Cardinal Johannes Willebrands, president of the Vatican Secretariat for Christian Unity, said the Polish-born pontiff was not invited to attend the ceremonies himself but will send representatives of the Holy See. John Paul has made clear that he will not visit the Soviet Union until the underground Ukrainian Catholic Church, suppressed by dictator Josef Stalin in 1946, is legalized.