Acts 1:1-11 / Mark 16:14-20
Ye men of Galilee, why stand you looking up to heaven? This Jesus, Who is taken up from you into heaven, said the two men in white garments, shall so come as you have seen Him going into heaven. On a certain way of reading, this pair of sentences, the question and the assertion, seem to be in conflict one with the other. After all, if Jesus shall indeed so come as we have seen Him going into heaven, then this means he will return descending from the sky even as he ascended up into the heavens. To this way of reading the text, the motive to look up to heaven seems assured precisely by the logic which the angels put forward to dissuade the apostles from a heavenword gaze.
Of course, what this suggests is that we have misread what the angels wanted the apostles, and indeed want us, to hear. Let us consider again the events of Jesus' Ascension. The apostles have just asked Jesus whether he, having been raised from the dead and having appeared to them for forty days, would at this time restore again the kingdom of Israel. Jesus' reply is clear, not in answering the question itself, but in insisting that this question is inappropriate for his disciples in via: It is not for you to know the times or moments which the Father hath put in His own power. What they are assured is not knowledge of the establishment of the kingdom, but rather an assurance of the presence of the Holy Spirit, a presence which will give warrant and credit to the Gospel they are commanded to preach. In My name, Jesus tells the eleven, they shall cast out devils; they shall speak with new tongues; they shall take up serpents; and if they shall drink any deadly thing, it shall not hurt them; they shall lay they hands upon the sick, and they shall recover ... But they going forth preached everywhere, the Lord working withal, and confirming the word with signs that followed.
So, how is it that Jesus shall so come as we have seen Him going into heaven that we ought not to stand ... looking up to heaven? The answer is in both the Acts and the Gospel. As Acts record it, while they looked on, He was raised up: and a cloud received Him out of their sight. As Mark presents it, the Lord Jesus, after He had spoken to them, was taken up into heaven and sitteth on the right hand of God. That is, in both accounts, the Ascension was unexpected, unannounced, and happened in the midst of his being present to them. That we know of his going up to heaven could and can only be known by our trust in them, by our assurance that the Lord is working withal not only in the witness of the apostles and their Gospels and letters, but even to this day in his Church, and in our faithful reception of that teaching as authoritatively taught by the Church universal. Said differently, Jesus was taken up to heaven in just the same way as he rose from the dead, and as Jesus upbraided the eleven with their incredulity and hardness of heart, because they did not believe them who had seen Him after He had risen again, so he calls the eyes of the eleven, and our eyes as well, away from heaven. He calls our eyes and our ears to be focused not on a personal assurance of the presence of the risen Lord and his glorious return, but, buttressed by supernatural faith to give credit to the authentic witnesses of Christ, our attention rather is to be on the proclamation of the Gospel to every creature, that those who are called will come to salvation: Go ye into the whole world and preach the gospel to every creature. He that believeth and is baptized shall be saved: but he that believeth not shall be condemned.
The Ascension, for all of its natural focus on the glorious entry of Christ into the Temple not made by human hands, for all of its rightful revelation of the fulfillment of the High Priestly work begun on Calvary, now bringing the Blood beyond all price into the true Holy of holies, not made by human hands, and there to plead our cause better than did the blood of Abel, is not meant to direct our hearts or our minds towards fretting about the day or time of his return. Rather, it is because our hearts and minds can be, and indeed by faith already are, safely secured in heaven above where Christ is, we can with unfettered freedom engage the creatures of the world and without fear or hesitation proclaim the Good News of eternal life in Jesus Christ.