In 1 John, the Apostle stresses over and over that love signifies the reality and vitality of a person’s faith. In 1:5-6 he writes that “God is light and in him is no darkness at all. If we say we have fellowship with him while we walk in darkness, we lie and do not practice the truth.” In 2:10 he fleshes out more clearly the quality of a truly believing community: “Whoever loves his brother abides in the light, and in him there is no cause for stumbling.” (Verse 10 is bracketed by verses 9 and 11 which both emphasize that the one who does not love is in the darkness.)
In 2:15 John cautions his audience to not direct their love towards worldly things (“the desires of the flesh and the desires of the eyes and pride in possessions”). He then spends considerable time warning about those unbelievers who might be – or had been – in the community of professing believers, but are not actually true Christians.
In 3:11 John cycles back to the idea of “love” (“the message that you have heard from the beginning”) and then goes on to make several litmus test statements:
14: We know that we have passed out of death into life, because we love the brothers.
17: If anyone has the world’s goods and sees his brother in need, yet closes his heart against him, how does God’s love abide in him?
4:7: Beloved, let us love one another, for love is from God, and whoever loves has been born of God and knows God.
12b: if we love one another, God abides in us and his love is perfected in us.
21: And this commandment we have from him: whoever loves God must also love his brother.
Many of these verses are well known scripture, and we are not surprised to be reminded that love for the Church is a symptom of the Holy Spirit’s residence within us. But the idea of “love” as action is often a nebulous concept and seems to be most often understood as anything done for someone else that the recipient subjectively views as kind or constructive (with something like “tough love” being an exception to this subjective test). That is not what John has in mind in his letter. When he refers to love there is an objective moral component to it. In 2:4-6 he outlines the backbone of the kind of love he will emphasize throughout:
Whoever says “I know [Jesus Christ]” but does not keep his Commandments is a liar and the truth is not in him, but whoever keeps his word, in him truly the love of God is perfected. By this we know that we are in him: whoever says he abides in him ought to walk in the same way in which he walked.
For good measure, John defines love again as he is closing out his letter (5:1-3):
Everyone who believes that Jesus is the Christ has been born of God, and everyone who loves the father loves whoever has been born of him. By this we know that we love the children of God, when we love God and obey his Commandments. For this is the love of God, that we keep his Commandments.
So this “love” that we are to have for fellow believers is rooted in keeping God’s commandments. We do not truly love if we are not truly obeying God – loving as he has called us to love. And quite unlike the worldly understanding of love, the existence of the love John is speaking of (perfected in a believer by God, 2:5, 3:12) is not dependant on the subjective experience of the recipient of that love. It is proven by its conformity to the character and commands of God.