The mysteries that God revealed to the apostles and prophets led to an outlook on the new covenant age that New Testament scholars often describe as “inaugurated eschatology” or “the now, but not yet.” Whatever terminology we may choose, we can see that Jesus and the writers of the New Testament taught that in God’s plan for the last days, the fulfillment of the age of the new covenant was to take place in three main stages.

First, the inauguration of the new covenant age was initiated in Jesus’ first coming and in the ministries of his apostles and prophets. This is why the New Testament speaks of the days of Jesus and his apostles as “the last days.” In Hebrews 1:1-2 the author of Hebrews referred to the time of Jesus' earthly ministry and of his readers as "these last days." As this passage indicates, with Jesus’ inauguration of the kingdom, the promised last days of the Old Testament had come upon the world.

The New Testament emphasizes that this inaugural phase of the new covenant age included all that Jesus accomplished in his incarnation, death, resurrection, ascension into heaven, and the outpouring of the Holy Spirit. This special time also included the ministries of the apostles and prophets in their foundational work for the church. In Ephesians 2:19-20, Paul put it this way:

God’s household [is] built on the foundation of the apostles and prophets, with Christ Jesus himself as the chief cornerstone.

Second, the continuation of the new covenant epoch extends throughout the entire period of church history. During this time, Christ spreads the church throughout the nations through the proclamation and transformative influence of the gospel. This is why the New Testament writers, in places like 2 Timothy 3:1-5, designated the entire period of church history as the last days. Listen to what it says there:

But mark this: There will be terrible times in the last days. People will be lovers of themselves, lovers of money, boastful, proud, abusive, disobedient to their parents, ungrateful, unholy, without love, unforgiving, slanderous, without self-control, brutal, not lovers of the good, treacherous, rash, conceited, lovers of pleasure rather than lovers of God — having a form of godliness but denying its power.

The sins listed here for “the last days” were sins that were occurring in Paul’s day, and that have continued to occur throughout history and into the present day.

Third, the last days of the new covenant age will reach their consummation when Christ returns and fulfills God’s ultimate purposes for all of history. This is why New Testament authors described the consummation of the kingdom at Christ’s return as “the last days.” In John 6:39, Jesus told his disciples:

This is the will of him who sent me, that I shall lose none of all that he has given me, but raise them up at the last day.

His reference to “the last day” points forward to that ultimate final day when he will return in glory, the dead will rise, and God will judge the world.