“Whoever does not love does not know God, for God is love.” (1 John 4:8, NRSV)
“We love because he first loved us. 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 4:19-21, NRSV)
Most of us think of love as an emotion. We treat it as if it's a feeling that happens to us rather than as a cognitive choice or an act of volition. By viewing love as simply an emotion, we absolve ourselves of any responsibility for deciding what we do with the love in our hearts. We see ourselves as powerless over our feelings instead of mastering the art of loving ourselves and others in healthy ways.
In reality, love is rooted in our creation in the image of God. 1 John tells us that God is love with an emphasis on the word "is." The very beingness of God is equal to love in its purest expression. Since God's image is in us, love is at the core of our nature. We could even go so far as to say that love is our default response to any given person or situation. If love is our default response, then why is love for one another so lacking in this world. I argue that it's not that love is lacking as much as love is selfishly misdirected.
To understand how love is best directed, let's look at how God loves. Whatever God wants for himself, God wants for us, too. When God instructs us to love him, he does so only after extending his perfect and unconditional love to us. God loves us first and then asks us to love him, too. God wants to be loved, but God also wants us to be loved.
In human terms, if I love as God does, then whatever I want for myself, I also desire for others. For example, if I want my children or grandchildren to attend quality schools, loving as God loves requires me to want quality schools for everyone's children or grandchildren, too. But it doesn't stop there. To love as God loves includes a willingness to work toward or sacrifice whatever is necessary so that all children can get a quality education. If I want it only for my children, then my love is misdirected selfishly only toward my desires. Even worse, if working toward my children getting a quality education somehow makes it more difficult for other people's children to get a quality education, even my love for my children becomes tainted and diminished. As a result, I do not love as God loves.
We have to choose to love as God loves, and that choice requires effort and sacrifice. It's not always easy to love others and want the very best for them, especially when they do not extend the same kind of love in return. Again, God is our example. Even when we turn our backs on God, God's love is constant. Therefore, God's admonition to love others is not contingent on them loving us in return. It's absolute. And it's also absolute that if we fail to love others, we can't claim to love God. To love God is to love him and everyone else he loves. No exceptions.