There are all sorts of understandings of what love is, but in his letter, John tells us what the author of love has demonstrated it to be. For Jesus Christ laid down his life for his people. If we consider how unworthy we are in the sight of God, not only unworthy, but rebellious sinners, it amazes us that he would do such a thing. This love carried out what was necessary, and without condition. This love was self-sacrificing, it involved the sacrifice of almighty God himself for sinful humanity.
If we are Christians, our love for others should mirror that of our Saviour, for his love should flow into us and through us to others. We should love others in an unconditional self-sacrificial way, seeing when they have a need. We should not be all words and no actions, if anything we should be all action and no words. Saying that, our sacrifice should have a purpose, and be for the good of others.
If our lives are a reflection of Christ’s, we can assurance we are his. If our lives bear no resemblance at all, we should wonder if we are his at all, for we can only know this love if we have faith in him, and we can only love as he did if his Spirit is working in us.