As we have already seen A Holy God must judge sin; and so the only just declaration that holy justice can declare is guilty. Since we are guilty before God from the moment we are conceived in our mother’s womb. We cannot expect any other judgment. So how does Jesus become the propitiation for us?
The answer lies in His being our representative. Jesus Christ as we have seen was and is a sinless man. You and I by faith enter into His sinless life. So by faith in Him we become a new man.
To help us understand this let’s look at it this way. Adam being the first man represents all of humanity within himself 1 Cor 15:22-23
22 For as in Adam all die, so in Christ all will be made alive.
So too does Jesus who being the first fruit of all who have faith in Him. Jesus is the divine representative of a new people. People who will bear the likeness of Himself
1 Cor 15:49
And just as we have borne the likeness of the earthly man, so shall we bear the likeness of the man from heaven.
Lets think of it in these terms. The President of the United States represents the people of the United States before the world. If he signs a treaty that declares us at peace with a nation then we as a people have signed that treaty in him, because he represents us.