Those who are not in love of Godhead, they must quarrel. That is the . . . because they are cats and dogs. You cannot expect any peaceful condition between cats and dogs. They will fight. So whatever they may be, so long they are fighting, that means they are not on the perfectional stage. Where is the fighting? If you love God, then you love everyone. That is the sign. Samaḥ sarveṣu bhūteṣu mad-bhaktiṁ labhate parām (BG 18.54). After attaining the stage of equality, then you can enter into the realm of loving God. Before that, you have to pass.
Just like before entering law college you have to become graduate, similarly, before entering the realm of devotional service you have to realize that all living entities are on the same platform. That is realization. You cannot make any distinction that, "This is lower," "This is higher." No. Paṇḍitāḥ sama-darśinaḥ (BG 5.18). When a person is fully learned, he does not make any distinction that, "He is human being, he is cow, he is dog, he is . . ." He sees that he is spirit soul covered in different dress. That's all. That is his vision, universal equality vision.