Huper (G5228) is the NT's great preposition of substitution and intercession. 'On behalf of' โ Christ died huper all; He intercedes huper the saints; the Spirit prays huper us. The word encodes the logic of the atonement: someone acting in the place of another, bearing what they could not bear, obtaining what they could not obtain.
Romans 5:8 declares the heart of the gospel: 'While we were still sinners, Christ died for [huper] us.' 2 Corinthians 5:21 adds the substitution: 'God made him who had no sin to be sin for [huper] us.' Romans 8:26-27 promises the Spirit intercedes for [huper] us. Hebrews 7:25 declares Christ 'always lives to intercede for [huper] them.' The Christian life is sustained by huper โ by Another acting on our behalf.