After talking about testing the spirits and false prophets in his first epistle, John gives us a litmus test for knowing whether or not someone actually knows God.
It comes down to this: to know God is to know love. To know love means to love others (emphasis added).
7 Dear friends, let us love one another, because love comes from God. Whoever loves is a child of God and knows God. (1 John 4:7 GNT)
Next, John puts a negative spin on it, saying we prove that we don’t know God if we don’t love…
8 Whoever does not love does not know God, for God is love. (1 John 4:8 GNT)
Notice that knowing God is not based on how much you know about God, or knowing your Bible inside and out, or having great faith that moves mountains, or in being “sold-out for Jesus.” All those things are good but, as Paul puts it, they avail nothing at all without love (1 Cor. 13:1-3).
The Greek word for love here, as you probably know, is agape (ἀγάπη). It means to show benevolence, to do good to others; goodwill; charitableness, acts of kindness.
Of course, this kind of love includes loving those who curse us, spitefully use us, persecute us, hate us, and those who want to be our enemies (Matt. 5:43-48).
John continues on by saying that we’re not fooling anybody but ourselves if we say we know God but hate anyone else (emphasis added):
20 If we say we love God, but hate others, we are liars. For we cannot love God, whom we have not seen, if we do not love others, whom we have seen. 21 The command that Christ has given us is this: whoever loves God must love others also. (1 John 4:20-21 GNT)
We cannot honestly say we know God and not love others. God will not let us get away with that. This is why He lets us be just as judgmental of others as we wish to be judged ourselves (Matt. 7:1-2).
We tend to think compartmentally, but God is fully relational. He’s never done anything alone. The Father has always loved the Son, and the Son has always loved the Father. And we’re all intimately connected together… individually members of one another…whether we want to see it that way or not. But it’s in truly knowing God where we finally see this reality.
20 At that day you will know that I am in My Father, and you in Me, and I in you. (John 14:20 NKJV)
23 I in them, and You in Me; that they may be made perfect in one, and that the world may know that You have sent Me, and have loved them as You have loved Me. (John 17:23 NKJV)
You might say that we shouldn’t judge a person’s relationship with God. That’s true. But Jesus also said we’ll probably find out what’s really going on inside the person whether that experience is a good one or not!
45 A good man out of the good treasure of his heart brings forth good; and an evil man out of the evil treasure of his heart brings forth evil. For out of the abundance of the heart his mouth speaks. (Luke 6:45 NKJV)
16 You will know them by their fruits. Do men gather grapes from thornbushes or figs from thistles? 17 Even so, every good tree bears good fruit, but a bad tree bears bad fruit. 18 A good tree cannot bear bad fruit, nor can a bad tree bear good fruit. (Matt. 7:16-18 NKJV)
And we can certainly judge ourselves by honestly looking at how we love others, to see if we’re actually following Jesus or something else. The fruit doesn’t lie.
Here’s the deal. You tend to take on the nature of the people you spend a lot of time with. John is simply saying that we can all tell if you’ve been hanging out with God by how much you love others. Why? Because God is love, and the fruit of knowing God is an ever increasing ability to love others the same way He loves them.