34 No one would think of preventing young Germans establishing a true ethnical community in a noble love of freedom and loyalty to their country. What We object to is the voluntary and systematic antagonism raised between national education and religious duty. That is why we tell the young: Sing your hymns to freedom, but do not forget the freedom of the children of God. Do not drag the nobility of that freedom in the mud of sin and sensuality. He who sings hymns of loyalty to this terrestrial country should not, for that reason, become unfaithful to God and His Church, or a deserter and traitor to His heavenly country. You are often told about heroic greatness, in lying opposition to evangelical humility and patience. Why conceal the fact that there are heroisms in moral life? That the preservation of baptismal innocence is an act of heroism which deserves credit? You are often told about the human deficiencies which mar the history of the Church: why ignore the exploits which fill her history, the saints she begot, the blessing that came upon Western civilization from the union between that Church and your people? You are told about sports. Indulged in with moderation and within limits, physical education is a boon for youth. But so much time is now devoted to sporting activities, that the harmonious development of body and mind is disregarded, that duties to one's family, and the observation of the Lord's Day are neglected. With an indifference bordering on contempt the day of the Lord is divested of its sacred character, against the best of German traditions. But We expect the Catholic youth, in the more favorable organizations of the State, to uphold its right to a Christian sanctification of the Sunday, not to exercise the body at the expense of the immortal soul, not to be overcome by evil, but to aim at the triumph of good over evil ( Rom . xii. 21) as its highest achievement will be the gaining of the crown in the stadium of eternal life (1 Cor. ix. 24).
Source: Mit Brennender Sorge (Vatican.va)