Another detail that Luke mentions here, from what Jesus and his disciples discussed during their time together, is the future of Israel in God’s purposes.
Several commentators find fault with the disciples for asking this question, but on what evidence they do so I cannot see. I don’t think it is valid to say that they would have asked a carnal question having spent so much time during these forty days being instructed by Jesus about the kingdom of God. The Saviour, certainly, does not find fault with them for asking it and neither does he say that Israel will not be restored in the future.
Why would they have asked this question? I think the answer is that the Old Testament promised both the coming of the Spirit and the restoration of Israel during the reign of the Messiah. Jesus was about to begin his reign from heaven, and he had intimated that the Spirit would come within a few days. Therefore it was natural for them to ask if the restoration of Israel would also occur then.
We should note two things from this matter. First, the apostles were acknowledging the sovereignty of Jesus because they believed that he would be the one who would restore Israel. This would be one of the actions that Jesus would do from heaven during his reign. The church has waited a long time for Jesus to perform this great work, but it will be wonderful when it happens (Rom. 11:11-15). We should be praying for and anticipating with delight that wonderful future day.
Second, Jesus reminds them that the Father works to his timetable, and there are many details within it that he has not revealed when they will happen (v. 7). This denial, however, should not diminish or remove our confidence in him. Today, we seem to be seeing the decline of Christianity in the western world, or so we are told. But these commentators don’t know the timetable of God. Our hope is in his plans and not in human speculations.