The atonement does not win or constrain the love of God. The love of God constrains to the atonement as the means of accomplishing love's determinate purpose.'
The view known as that of hypothetical necessity maintains that God could have forgiven sin and saved his elect without atonement or satisfaction-other means were open to God to whom all things are possible. But the way of the vicarious sacrifice of the Son of God was the way which God in his grace and sovereign wisdom chose because this is the way in which the greatest number of advantages concur and the way in which grace is more marvellously exhibited.
while it was not inherently necessary for God to save, yet, since salvation had been purposed, it was necessary to secure this salvation through a satisfaction that could be rendered only through substitutionary sacrifice and blood-bought redemption.'
God is love. But the supreme object of that love is himself. And because he loves himself supremely he cannot suffer what belongs to the integrity of his character and glory to be compromised or curtailed. That is the reason for the propitiation. God appeases his own holy wrath in the cross of Christ in order that the purpose of his love to lost men may be accomplished in accordance with and to the vindication of all the perfections that constitute his glory. "Whom God hath set forth to be a propitiation through faith in his blood to show his righteousness . . . that he might himself be just,...
Note: God is love... and He supremely loves Himself.