This refers to Christ, who is the Desire of all the nations (Mal. 3:1b). Even though the nations do not know Christ, they still desire Christ. All people desire to have peace and a good life with virtues such as light, love, patience, humility, meekness, endurance, joy, and righteousness. Since Christ is the reality of all these things, for the nations to desire these things means that, unconsciously, they desire Christ.
The coming of Christ as the Desire of all the nations depends on the return of God’s people from their captivity in Babylon and the recovery of the building of God’s house. Christ came the first time, in His incarnation, through the return of a remnant of Israel to Jerusalem from their captivity in Babylon for the rebuilding of the temple. He will come the second time through the return of a remnant of His New Testament elect from their captivity in the religious Babylon (Rev. 17) to the proper ground of the church for the recovery of the building of the church, God’s spiritual house (1 Tim. 3:15; 1 Pet. 2:5).