The two tests

 Ponder this! 

"In this the children of God are manifest, and the children of the devil. Whosoever is not just is not of God, or he that loveth not his brother" [1 Jh. 3:10]

"The two tests are, the doing righteousness, and loving his brother. Righteousness and charity are of God, unrighteousness and hatred are of the devil. Righteousness is here taken in its widest sense, as including all virtues. But St. John here states that among all kinds of righteousness none shows more that we are the sons of God, than charity and the love of our neighbour, as the contrary vices show us to be the children of the devil. And hence S. John, the beloved disciple, breathes forth love only. Hear S. Augustine (in loc.): “Love alone distinguishes between the children of God and the children of the devil. Let all sign themselves with the sign of the cross, let all answer Amen, let all sing Alleluia, let all be baptized, let all go to church, let all build churches. Yet the sons of God are distinguished from the children of the devil only by charity. They who have charity are born of God, they who have it not are not born of God. Have what thou wilt; if this alone thou have not, it profiteth thee nothing. If thou hast not anything else, have this: thou hast fulfilled the law.” [ C. a Lapide]