This epistle’s primary theme is how a person may know that they are truly saved.  There are many tests which John applies, whereby a person can discern whether he has passed from death unto life.  Here at the beginning of chapter 5, he returns to one of the fundamentals of the Christian faith, telling us that every person who believes that Jesus is the Christ (“Christ” meaning God’s anointed Messiah) is born of God.  He has had that great work done in him of which Jesus spoke to Nicodemus, that work of regeneration without which no man can see the kingdom of God.  This shows that belief in Christ is not simply the option of man’s unaffected free will.  His belief in Jesus as the Christ is God is based upon his receipt of the grace of the new birth.  Only a man who is born of water and of the Spirit can truly believe in Jesus as God’s Christ, and receive and worship Him as such.

John could never be numbered among the multitudes of our day who fancy that a person can make everything well with his soul simply by believing on Jesus, and then go on living the rest of his life without paying any attention to the commands of God.  He solemnly informs us that, if we love the One by Whom we are begotten, then we must also love those who are begotten by Him.  This language may seem somewhat difficult at a glance, and yet it is easy of interpretation.  All Christians confess that they love God, Who has regenerated them and granted them an inheritance among the saints in light.  As a further consequence of this new birth, John argues, if we love the gracious God Who has made us new creatures in Christ, then we will also love those who have partaken of the same grace.  To put it plainly: If we love God, then we will also love the people of God, who reflect His image.