John gets more specific here in verses 12-14, addressing children, fathers, and young men. Over the next few entries, we'll be discussing these characters more in depth. Some might argue that John is writing only to men here, since he uses the masculine terms; and among these, some accept this as a matter of fact while others gnash their teeth. A great many contemporary readers suggest that John is addressing men and women, as Paul does, while simply using masculine terms as a generalization. I choose not a side on this matter, but only offer (as I'm sure others have) that whether or not John was referring to all, the truth expressed here is applicable to all and so we should quit with the boasting, gnashing teeth, and people pleasing, and simply read the text prayerfully.
With that settled, John say, “I'm writing to you kids because your sins are forgiven,” and then later, “I wrote to you kids because you've known the Father.” The intriguing thing to me here is that it's entirely independent of the child's responsibility or action. Instead, it is the relationship with the Father, as clarified in verse 13, that is the focus. Notice it doesn't say, “because you confessed your sins” or even “you asked for forgiveness.” It says we were forgiven on account of His Name. While John makes it very clear in other verses that our walk with the Lord needs to be right, he brings us back to the basics here. It is not our power, but the Lord's which saves us and guides us home. It is not our will, but His which gives us purpose and fulfillment. And it is not our sweat, but His blood which cleanses us from all unrighteousness.
We all know the analogy, courtesy of Jesus himself, of ourselves being as children in the presence of God. The simplicity and helplessness are the keys. We are dependent wholly on His grace to see us through, and this is why John addresses the children here. It is regularly assumed that he is referring to new believers, but I'd like to suggest that he is referring to the weak believer – new and old. After all, a warrior can become injured and require care as if he were a child. We go through seasons of taking on the world and other seasons of needing the milk, as it were. The rest of John's letter is a memorandum of age-old truths, so it only makes sense that this too would be a sort of reminder, intended for the feeble soul. We are all but helpless babes, leaning (as the old hymn sings) on the everlasting arms. We are forgiven because of His perfect Son on account of His unfathomable name. And so in this we are encouraged to grow in the Lord, on account of His name, to mature into young men and, in time, fathers.