My little children, I am writing these things to you so that you may not sin. And if anyone sins, we have an Advocate with the Father, Jesus Christ the righteous; and He Himself is the propitiation for our sins; and not for ours only, but also for those of the whole world.
John makes it clear that it is not proper or right to sin. But with corrupt hearts living amid the temptations of this world all are liable to sin. And when we are conscious of sin our minds should not yield to despair. The atonement made by the Redeemer covers all kinds of sin, and under the deepest consciousness of guilt and of personal unworthiness we may be assured that we have an advocate on high.
This is not like an earthly advocate who either claims his client’s innocence or makes excuse for the behavior. Christ admits the guilt of those for whom he becomes the advocate, to the full extent charged on them by the law of God. He does not attempt to hide or conceal it. He makes no apology for it. But being completely just he must also ensure that no wrong be charged to the character of God if we are not punished as we deserve and are instead pardoned. His sufferings and death on behalf of sinners have done as much to honor the law and maintain the truth and justice of God as if the offenders themselves had suffered the full penalty of the law.
Propitiation basically means “atoning sacrifice”. The mercy seat of the Tabernacle where God met man was called the propitiation. Christ is our mercy seat, where God meets us in mercy and forgiveness. The idea is that there is anger or wrath, and sacrifice is needed to turn away that wrath. We see this pictured in the blood offerings carried out in the Jewish scriptures. Only blood would turn away wrath for sins, but there was no full atonement until the sacrifice of Christ. All previous sacrifices before were temporary atonement.
The phrase "the whole world" embraces all people, not only the elect. His propitiation extends as widely as sin extends. This cannot be correctly interpreted to mean that all will be forgiven, but that forgiveness is available to all. Gratitude for our own forgiveness should propel us to share the same knowledge with the world!