How is that possible?

The righteous requirements of the Law have been met in him in order that the righteous requirements of the Law might be met fully in us. This declaration by Paul is breathtaking in its precise correspondence with the idea of recapitulation and its outcome. But there is more. We have emphasized that Paul’s gospel is not about human potential or human possibility but about the power of God. Here in Romans 8:4 is a clear illustration. Our own “recapitulation,” the new life in Christ, is only possible through the power of the third person of the Trinity, the Holy Spirit.—Fleming Rutledge, The Crucifixion, 553 (emphasis original)