“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.” 1 John 3.10
It is very easy, simple and practical to recognize. The children of God practice righteousness and love. They live in purity and peace. But the children of the devil practice injustice and hatred. They live in error, amid fights and pains.