7 From the beginning the Church spared no pains to make the Christian people, in a matter of such high importance, accept and firmly hold the true teachings of Christ and the Apostles. And now through the new Adam, who is Christ, there is established a brotherly union between man and man, and people and people; just as in the order of nature they all have a common origin, so in the order which is above nature they all have one and the same origin in salvation and faith; all alike are called to be the adopted sons of God and the Father, who has paid the self same ransom for us all; we are all members of the same body, all are allowed to partake of the same divine banquet, and offered to us all are the blessings of divine grace and of eternal life. Having established these principles as beginnings and foundations, the Church, like a tender mother, went on to try to find some alleviation for the sorrows and the disgrace of the life of the slave; with this end in view she clearly defined and strongly enforced the rights and mutual duties of masters and slaves as they are laid down in the letters of the Apostles. It was in these words that the Princes of the Apostles admonished the slaves they had admitted to the fold of Christ. "Servants, be subject to your masters with all fear, not only to the good and gentle, but also to the forward."(10) "Servants, be obedient to them that are your lords according to the flesh, with fear and trembling in the simplicity of your heart, as to Christ. Not serving to the eye, but as the servants of Christ, doing the will of God from the heart. With a good will serving as to the Lord, and nor to men. Knowing that whatsoever good thing any man shall do, the same shall he receive from the Lord, whether he be bond or free."(11) St. Paul says the same to Timothy: "Whosoever are servants under the yoke, let them count their masters worthy of all honor; lest the name of the Lord and his doctrine be blasphemed. But they that have believing masters, let them not despise them because they are brethren, but serve them the rather, because they are faithful and beloved, who are partakers of the benefit. These things teach and exhort."(12) In like manner he commanded Titus to teach servants "to be obedient to their masters, in all things pleasing, not gainsaying. Not defrauding, but in all things showing good fidelity, that they may adorn the doctrine of God our Saviour in all things."(13)
Source: In Plurimis (Vatican.va)