Or, Who shall descend into the deep? (that is, to bring up Christ again from the dead.)

People's New Testament

10:7 Or, Who shall descend into the deep? Another stumbling block with the Jews was the death and burial of Christ. When Jesus died on the cross, they held it to be proof that he was not the Christ.

Bring up Christ again from the dead. They still were wont to demand that they should see the Risen Christ with their own eyes, or that he be produced from the realms of the dead. To have met the demands of the Jews would have been sight rather than faith.

Jamieson-Fausset-Brown Bible Commentary

7. Or, Who shall descend, &c.-another case of impossibility, suggested by Pr 30:4, and perhaps also Am 9:2-probably proverbial expressions of impossibility (compare Ps 139:7-10; Pr 24:7, &c.).

Matthew Henry's Concise Commentary

10:5-11 The self-condemned sinner need not perplex himself how this righteousness may be found. When we speak of looking upon Christ, and receiving, and feeding upon him, it is not Christ in heaven, nor Christ in the deep, that we mean; but Christ in the promise, Christ offered in the word. Justification by faith in Christ is a plain doctrine. It is brought before the mind and heart of every one, thus leaving him without excuse for unbelief. If a man confessed faith in Jesus, as the Lord and Saviour of lost sinners, and really believed in his heart that God had raised him from the dead, thus showing that he had accepted the atonement, he should be saved by the righteousness of Christ, imputed to him through faith. But no faith is justifying which is not powerful in sanctifying the heart, and regulating all its affections by the love of Christ. We must devote and give up to God our souls and our bodies: our souls in believing with the heart, and our bodies in confessing with the mouth. The believer shall never have cause to repent his confident trust in the Lord Jesus. Of such faith no sinner shall be ashamed before God; and he ought to glory in it before men.