When we hear these words of Jesus, we usually focus on the word "least." However, we should especially accent the word "brothers," that is, "brothers and sisters." In this Scripture passage, Jesus taught that on Judgment Day He will judge us based on our love not for the poor in general but specifically for our Christian brothers and sisters in need. When the Lord teaches us about love, He makes the same point: "The way we came to understand love was that He laid down His life for us; we too must lay down our lives for our brothers" (1 Jn 3:16).
Paul learned this from Jesus and taught: "While we have the opportunity, let us do good to all men — but especially those of the household of the faith" (Gal 6:10). As Christians, we love all people, even our enemies, but the Lord wants us to reserve a special place in our hearts for our brothers and sisters in Christ. Because we are baptized brothers and sisters in Christ, we can have a depth of relationship with them impossible with those not baptized into brotherhood and sisterhood in Christ.
We must take our Christian brotherhood and sisterhood practically, seriously, and literally. Otherwise, why should we take our baptismal sonship and daughterhood seriously? If we are only figuratively but not literally God's children, then Christianity is only a shadow of what the Lord has promised us. A lived baptismal brotherhood and sisterhood is essential for a fully real Christian life. Therefore, let us love all the "brethren," including the least of them.