The Apostle John’s teaching here is at once simple and deep. The simplicity isn’t because John was a simpleton; and the depth isn’t a secret knowledge intended only for a scant few. We find here a depth that comes from maturing faith and love. A bride and groom avow their love on their wedding day, but as it is nurtured year upon year, decade upon decade, the depth of that trust and love grows sweeter, truer, lovelier. That, in part, is how Scripture teaches us to understand the doctrine of assurance of grace.