But of Him are ye in Christ Jesus, who of God is made unto us wisdom, and righteousness, and sanctification, and redemption. 1 Corinthians 1:30
The church is not an organization with Jesus Christ as its president. The church is an organism with Jesus Christ as its head. We are in Him and He is in us. The victory He won on the cross was for us.
When Jesus went to the cross, He wasn’t fighting the battle for Himself. He didn’t need to overcome Satan. He fought it on your behalf. He made the transaction, often called “the divine exchange”:
“What language shall I borrow to thank Thee, dearest Friend,
For this Thy dying sorrow, Thy pity without end?
O make me Thine forever, and should I fainting be,
Lord, let me never, never outlive my love for Thee.”