Among the many errors which derive from the poisoned source of religious and moral agnosticism, We would draw your attention, Venerable Brethren, to two in particular, as being those which more than others render almost impossible or at least precarious and uncertain, the peaceful intercourse of peoples.
The first of these pernicious errors, widespread today, is the forgetfulness of that law of human solidarity and charity which is dictated and imposed by our common origin and by the equality of rational nature in all men, to whatever people they belong, and by the redeeming Sacrifice offered by Jesus Christ on the Altar of the Cross to His Heavenly Father on behalf of sinful mankind.
In fact, the first page of the Scripture, with magnificent simplicity, tells us how God, as a culmination to His creative work, made man to His Own image and likeness (cf. Genesis i. 26, 27); and the same Scripture tells us that He enriched man with supernatural gifts and privileges, and destined him to an eternal and ineffable happiness. It shows us besides how other men took their origin from the first couple, and then goes on, in unsurpassed vividness of language, to recount their division into different groups and their dispersion to various parts of the world. Even when they abandoned their Creator, God did not cease to regard them as His children, who, according to His merciful plan, should one day be reunited once more in His friendship (cf. Genesis xii. 3).
The Apostle of the Gentiles later on makes himself the herald of this truth which associates men as brothers in one great family, when he proclaims to the Greek world that God “hath made of one, all mankind, to dwell upon the whole face of the earth, determining appointed times, and the limits of their habitation, that they should seek God” (Acts xvii. 26, 27).
A marvelous vision, which makes us see the human race in the unity of one common origin in God “one God and Father of all, Who is above all, and through all, and in us all” (Ephesians iv. 6); in the unity of nature which in every man is equally composed of material body and spiritual, immortal soul; in the unity of the immediate end and mission in the world; in the unity of dwelling place, the earth, of whose resources all men can by natural right avail themselves, to sustain and develop life; in the unity of the supernatural end, God Himself, to Whom all should tend; in the unity of means to secure that end.
It is the same Apostle who portrays for us mankind in the unity of its relations with the Son of God, image of the invisible God, in Whom all things have been created: “In Him were all things created” (Colossians i. 16); in the unity of its ransom, effected for all by Christ, Who, through His Holy and most bitter passion, restored the original friendship with God which had been broken, making Himself the Mediator between God and men: “For there is one God, and one Mediator of God and men, the man Christ Jesus” (I Timothy ii. 5). –from Summi Pontificatus(1939)