Complex sentence: By 1937, the church hierarchy had become highly disillusioned and Pope Pius XI issued the "Mit brennender Sorge" encyclical-condemning racism, and accusing the Nazis of violations of the Concordat and of "fundamental hostility to Christ and His Church".
Split into simpler sentences: By 1937, the church hierarchy became highly disillusioned and Pope Pius XI issued the "Mit brennender Sorge" encyclical. It condemned racism, accused the Nazis of violations of the Concordat and of "fundamental hostility to Christ and His Church".