“After he had said this, while they were watching, he was lifted up and a cloud hid him from their sight. As they were still staring into the sky while he was going, suddenly two men in white clothing stood near them and said, “Men of Galilee, why do you stand here looking up into the sky? This same Jesus who has been taken up from you into heaven will come back in the same way [houtōs eleusetai hon tropon] you saw him go into heaven.” Then they returned to Jerusalem from the mountain called the Mount of Olives (which is near Jerusalem, a Sabbath day’s journey away).” (Acts 1:9–12)
Many interpreters, surprisingly, misconstrue this passage meaning that Jesus will descend to the Mount of Olives.
But the text is not ambiguous. It is speaking of the manner by which he will return—the clouds (cf. Matt 24:29–31; Luke 21:27; 1 Thess 4:17; Rev 14:14–16).
One reason for this misinterpretation is another misinterpretation from Zech 14:4:
“On that day his feet will stand on the Mount of Olives that lies to the east of Jerusalem, and the Mount of Olives will be split in half from east to west, leaving a great valley. Half the mountain will move northward and the other half southward.” (Zech 14:4)
Notice that the passage does not say anything about Jesus “descending” to the Mount of Olives. This is assumed by so many interpreters, especially posttribulationists.
When Jesus physically descends to earth (whether it is Egypt, Mount Sinai, or some other vicinity south of Israel), he will lead a Jewish remnant up to Israel and eventually “stand” on the Mount of Olives and then protect his Jewish remnant (Zech 14:5).
I hope these two brief observations help to understand these two passages more accurately.