Beloved, let us love one another, because love is from God; everyone who loves is born of God and knows God. Whoever does not love does not know God, for God is love. No one has ever seen God; if we love one another, God lives in us, and his love is perfected in us.Love brothers and sisters? Wait - all of them?
God is love, and those who abide in love abide in God, and God abides in them. Those who say, ‘I love God’, and hate their brothers or sisters, are liars; for those who do not love a brother or sister whom they have seen, cannot love God whom they have not seen. The commandment we have from him is this: those who love God must love their brothers and sisters* also. (1 John 4:7-8; 12; 16b; 20-21)
And what is the standard of love? How is love demonstrated? 1 Corintians13:1-13 comes to mind. But, let me get more explicit. Is it first about what is good, healthy, life-giving for the other? Does one rejoice, not for his or her own joy, but for the joy of the other? Or weep for the sorrow of the other? Does one sit long hours at the sickbed, or drive to appointments, or fix a meal? Does one stay for years, to the point of sitting with the dying, and mourning in the loss, to the point of losing some part of her or his identity?
That is love enough to convince me. That looks like love to me, regardless of the exact description of the relationship, of its legal standing or its social acceptability, or just how it's physically expressed. That seems to me to be love; and love is of God, for God is love.