15 This Jesus Christ who is gone up shall come again, not from earth but from heaven: and I say, “not from earth,” because there are many Antichrists to come at this time from earth. For already, as you have seen, many have begun to say, I am the Christ: and the abomination of desolation is yet to come, assuming to himself the false title of Christ. But look thou for the true Christ, the Only-begotten Son of God, coming henceforth no more from earth, but from heaven, appearing to all more bright than any lightning and brilliancy of light, with angel guards attended, that He may judge both quick and dead, and reign in a heavenly, eternal kingdom, which shall have no end. For on this point also, I pray you, make yourself sure, since there are many who say that Christ's Kingdom has an end.
Of the Holy Ghost.
Source: Catechetical Lectures (New Advent)