These antichrists left our group [i.e., withdrew their fellowship from us], but they were not [really a part] of us, for if they had been, they would have continued [to participate] with us. But, by their leaving us, it proved that none of them were [really] a part of our group [after all].

not [hate each other] the way Cain did, who belonged to the evil one [i.e., Satan], when he murdered his brother [Abel]. And why did he murder him? It was because his [own] actions were evil and his brother's were righteous [See Heb. 11:4].