10 In this the children of God and the children of the devil are manifest: Whoever does not practice righteousness is not of God, nor is he who does not love his brother. 11 For this is the message that you heard from the beginning, that we should love one another… (1 John 3:10–11, NKJV)
There are obvious differences between the children of God, and the children of the devil. This passage expresses those differences negatively. The person who does not practice righteousness, and the one who does not love his brother, is “not of God.” This is entirely consistent with the apostle’s declaration in Acts 10:35, that “whoever fears Him and works righteousness is accepted by Him.” Practicing righteousness is equivalent to practicing truth, and walking in the light (1 John 1:6-7). Christians live their profession of faith by walking in truth, otherwise, they are “not of God,” and are without God’s approval. For you see, it is sin not to practice righteousness (1 John 3:7-8; James 4:17). As we practice righteousness, we must love our brethren, even as Jesus commanded from the beginning (1 John 13:34-35). The devil’s children do not practice righteousness or brotherly love. To them, these are unnecessary for God’s acceptance. It is a great deception to say how one lives as a Christian does not impact one’s divine approval now, and eternally. May we practice righteousness, and love our brethren. By this, we know we are of God.