Again, he touches the point of the Resurrection, since this was the most encouraging hope to the hearer, and gave him a security from what had happened unto Christ. Now be not thou afraid because you are compassed about with a dead body. Let it have the Spirit, and it shall assuredly rise again. What then, shall the bodies which have not the Spirit not rise? How then must “all stand before the judgment-seat of Christ?” or how will the account of hell be trustworthy? For if they that have not the Spirit rise not, there will not be a hell at all.
What then is it which is said? All shall rise, yet not all to life, but some to punishment and some to life. This is why he did not say, shall raise up, but shall quicken. And this is a greater thing than resurrection, and is given to the just only. And the cause of this honor he adds in the words, “By His Spirit that dwells in you.” And so if while here thou drive away the grace of the Spirit, and do not depart with it still safe, you will assuredly perish, though thou dost rise again. For as He will not endure then, if He see His Spirit shining in you, to give you up to punishment, so neither will He allow them, if He see It quenched, to bring you into the Bride-chamber, even as He admitted not those virgins.
Source: Homilies on Romans (New Advent)