In 1 John 4 we learn that “God is love”, which is in fact the second attempt at defining God in this discourse, the first coming at 1.5 where we heard ‘God is light’ and we may also rightly compare Jn. 4.24 where we are told God is spirit, a statement about God’s metaphysical nature, where as the two other predications are about God’s character.
While we might be tempted to think that this phrase means that God is loving, and so defined by his loving activities, and while that is true, it would seem that this phrase means something more. God not merely possesses or expresses love, love is a term which seems to embrace all God is. Yet still God is not really being defined here by an abstraction, nor is it a claim that the reverse of this statement is true (namely that ‘love is God’). What may be meant by ‘God is love’ is in part that “if the characteristic divine activity is that of loving, then God must be personal, for we cannot be loved by an abstraction, or by anything less than a person…But to say ‘God is love’ implies that all his activity is loving activity. If he creates, he creates in love; if he rules, he rules in love; if he judges, he judges in love. All that he does is the expression of his nature, which is— to love.” One more thing—the definition of love proceeds from God and works its way down to us—‘not that we loved God but that God loved us and sent his Son’.
Exhibit A of the loving character of God, paradoxically enough, is that he sent his Son to die for a sinful and ungrateful world. Vss. 9-10 stress first that Jesus was sent so that we might have life through him, and secondly that God sent his Son as a sacrifice of atonement to propitiate divine anger about sin. If God is love, then it is hardly a surprise that God is supremely and righteously angry with our sinning because it destroys the love relationships we have with God and with each other as well. We have here statements that are akin to what we find in Jn. 3.16-17. Love and life are the polar opposites of hate and death, and yet the substitutionary and atoning death of Jesus is the prime example of God’s love for us.
J. Denny long ago put it this way: “ So far from finding any kind of contrast between love and propitiation, the apostle can convey no idea of love to anyone except by pointing to propitiation—love is what is manifested there…For him to say ‘God is love’ is exactly the same as to say “God has in His Son made atonement for the sin of the world.” If the propitiatory death of Jesus is eliminated from the love of God, it might be unfair to say that the love of God is robbed of all meaning, but it is certainly robbed of its apostolic meaning. It has no longer that meaning which goes deeper than sin, sorrow, and death, and which recreates life in the adoring joy, wonder, and purity of the first Epistle of John.”
Instead of physically seeing the Father our author stresses that if we fulfill the commandment to love one another then we know and experience the presence of God in our midst and God’s love is thereby made complete, or brought to perfect expression or had its full intended effect (cf. 2.5 and 3.17). The circuit of God’s love is brought to completion when we love each other. If we take the several statements about perfect or complete love together (2.5, here and 4.17-18) the net effect is this: “Obedience, active love, confidence, these three point to the same fact. Where the one is the other is. The source of all is the full development of the divine gift of love.”