As we have discovered in previous readings, the theme of love runs throughout the New Testament. In today's reading, the very nature of God is described as love. In fact, to know love is to know God, according to John. However, it is very important that we recognize that John is referring to a specific kind of love, which was manifested by God in the giving of his Son, Jesus Christ. As we have previously observed, the love that was manifested through Christ was agape - self-giving, sacrifical love. It is this self-giving, sacrificial love that constitutes the very essence of God himself.
In the Christian life, the agape love that has been manifested through Christ is not confined to our private, individual relationship with God. But rather, this amazing love must now be manifested in our lives as children of God. In fact, John tells us that even though no one has seen God, the very life of God is present among those who love each other. The language of John's epistles evokes a sense of intimacy with God and one another, an intimacy that is only possible through Christ. We do not naturally love as Christ has loved us, but his love is formed in us as we abide in him and we, in turn, love one another in the same manner.
Now for a word about heresy! In the early Church there were numerous and various responses to the question "Who is Jesus?" By the end of fifth century, the belief that Jesus was both fully divine and fully human was fairly well established as Christian orthodoxy. However, in the first few centuries of the Church, these issues were hotly debated. One group believed that Jesus was fully divine, but only appeared to be physically human. This belief became known as docetism, which comes from a Greek word that means "to appear or to seem." According to docetism, Jesus only appeared to have a physical body and therefore only appeared to actually die on the cross. This view was rejected by the early Church as heresy. Portions of the First Letter of John may have been directed at this particular issue. John says, "every spirit that confesses that Jesus Christ has come in the flesh is from God" (4:2). The emphasis placed on the language "in the flesh" may be a direct attack against the heresy of docetism.