What is the historical context of Jesus’ statement to his disciples, “there are some standing here who will not taste death until they see that the kingdom of God has come with power?” What are the theological implications of understanding this passage in its first century context?
The historical context of “the kingdom of God coming with power” in the lifetime of “some who were standing there” is indeed past to us, and was fulfilled at the destruction of the temple in AD 70. This is not to say that the destruction of the temple was the coming of the kingdom, but rather that it was the visible sign that all that had been written had been fulfilled. In other words, these events were not the substance of the coming of the kingdom, but rather the visible sign of its coming. Of course, the sign itself was a display of God's power, no doubt. In fulfillment of Christ's words, "not one stone was left upon another" (cf. Mark 13:2). But it was the destruction not of the temple building itself, but of what it represented--the OT law and commandments being abolished, and the "rulers of that age being brought to nothing" (cf. 1 Corinthians 2:6)--which ushered in the reign of Christ by the Gospel, and the establishment of "his government and peace which shall have no end" (Isaiah 9:6). The temple’s demise signified that the Old Covenant Age had passed away, and the New Covenant Age had begun. Jesus had indeed “made all things new” (cf. Revelation 21:5).
How one understands the nature of the kingdom will determine whether they believe it has fully come. For example, if one views kingdom promises as physical or geo-political in nature, then they may see a yet future fulfillment. Whereas if one sees kingdom promises as spiritual in nature, and applying to a kingdom “not of this world” (cf. John 18:36), and which came “without observation” (cf. Luke 17:20), which exists within the hearts of God’s people (cf. Luke 17:21), and is experienced in their communion with God and with one another in His presence (cf. Psalm 16:11; Romans 14:17; Revelation 3:20; 21:3) then they will understand that God’s kingdom has fully come. However to say the kingdom has fully come is not to say it is not ever growing and expanding, as more and more enter (cf. Isaiah 60:11; Revelation 21:25); for “His authority shall grow continually, and there shall be endless peace for the throne of David and his kingdom. He will establish and uphold it with justice and with righteousness from this time onward and forevermore. The zeal of the Lord of hosts will do this” (Isaiah 9:7).