I have written to you, fathers, because you know him who is from the beginning. I have written to you, young men, because you are strong, and the word of God remains in you, and you have overcome the evil one.

 So, then, John means that we are assured of forgiveness because we know the character of Jesus Christ. We know that in him we see God. We see in him sacrificial love and patient mercy; therefore we know that God is like that; and, therefore. we can be sure that there is forgiveness for us. 