I know it sounds harsh to speak of God killing Jesus. Killing so easily connotes sinning and callous cruelty. God never sins. And he is never callous. The reason I say that God killed his own Son is because Isaiah 53 uses this kind of language. Verse 4: ‘We esteemed him stricken, smitten by God.’ God smote him. Verse 6: ‘The Lord laid on him the iniquity of us all.’ Verse 10: ‘It was the will of the Lord to crush him; he has put him to grief.’ God smote him. God crushed him.

This is the very center of our Christian faith: God substituted Jesus for us.

John Piper