9 May He open the same more fully, and dawn upon us as He begins to do! “Verily, verily, I say unto you, The hour is coming, and now is.” We did look for a resurrection of the dead in the end, for so we have believed; yea, not we looked, but are manifestly bound to look for it: for it is not a false thing we believe, when we believe that the dead will rise in the end. When the Lord Jesus, then, was willing to make known to us a resurrection of the dead before the resurrection of the dead, it is not as that of Lazarus, or of the widow's son, or of the ruler of the synagogue's daughter, who were raised to die again (for in their case there was a resurrection of the dead before the resurrection of the dead); but, as He says here, “has,” says He, “eternal life, and comes not into judgment, but is passed from death into life.”
To what life? To life eternal. Not, then, as the body of Lazarus: for he indeed passed from the death of the tomb to the life of men, but not to life eternal, seeing he was to die again; whereas the dead, that are to rise again at the end of the world, will pass to eternal life. When our Lord Jesus Christ, then, our heavenly Master, the Word of the Father, and the Truth, was willing to represent to us a resurrection of the dead to eternal life before the resurrection of the dead to eternal life, “The hour comes,” says He.
Doubtless you, imbued with a faith of the resurrection of the flesh, looked for the hour of the end of the world, which, that you should not look for here, He added, “and now is.” Therefore He says not this, “The hour comes,” of that last hour, when “at the command and the voice of the archangel and the trump of God, the Lord Himself shall descend from heaven, and the dead in Christ shall rise first; then we who are alive and remain shall be caught up together with them in the clouds, to meet Christ in the air: and so shall we be ever with the Lord.” That hour will come, but is not now.
But consider what this hour is: “The hour comes, and now is.” What happens in that hour? What, but a resurrection of the dead? And what kind of resurrection? Such that they who rise live for ever. This will be also in the last hour.
Source: Tractates on the Gospel of John (New Advent)