Father Cassilly writes: “Children of the same parentage belong to one family and are called brothers and sisters. All the members of the human race, since they are sprung from Adam and Eve, form but one family. Of whatever race or tribe they be, of whatsoever condition in life, whether kings or peasants, rich or poor, white, brown or black, they can all trace their lineage back to the same ancestry and claim kinship in blood.”
“Christians are even more closely related. Being regenerated in grace and born anew into the likeness of their heavenly Father, they are His children by a very special title. Hence the Apostles, Saints Paul, John, James and Peter were inspired to address the Christians as ‘brethren.’ . . . The foundation of our brotherhood St. Paul bases on the fact that we are made conformable to the image of God’s Son: ‘that He might be the first-born amongst many brothers’ (Rom 8:29). Christ is by nature the Son of God, and we by grace are like unto Christ, so that He is our elder brother; both He and we having the same Father. If we Christians, then, all have the same brother, Christ, and the same Father, God, we are truly brothers and sisters one to another. From this beautiful doctrine it follows that amongst Christians, ‘There is neither Jew nor Greek; there is neither bond nor free; there is neither male nor female. For you are all one in Christ Jesus’ (Gal 3:28).”
“Now there would seem to be no need of a precept for brothers to love one another. Nature begets this mutual affection in them. And yet estrangement may and sometimes does occur between members of the same household. . . . Love, rather than blood relationship, becomes in them an index of brotherhood. Hence, Mutual affection must be the distinguishing mark of brethren in the faith. And so necessary is this that Christ made it a law—’A new commandment I give unto you: That you love one another, as I have loved you’ (John 13:34). This is the vital test or criterion by which He wished men to recognize His disciples.”
Quotations from Francis Cassilly, A Story of Love, 2d ed. (St. Louis: B. Herder, 1917).