Therefore, as for you, let that remain in you which you heard from the beginning. If that which you heard from the beginning remains in you, you also will remain in the Son, and in the Father.

 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. 