When will the Old Testament believers be raised from the dead?

If we are right in taking the expression, “in Christ,” as a New Testament term, and therefore “the dead in Christ” (1 Thessalonians 4: ) as referring only to New Testament saints, when will the Old Testament saints be raised?

In 1 Corinthians 15:23 we have the general truth that Christ is “the first- fruits” of the Resurrection, “afterward, they that are Christ’s at His coming.” This expression seems to include here the whole completed Second Coming, when the first Resurrection will be finished.

This will have taken place in different stages and categories. Thus, supposing the Resurrection in 1Thessalonians 4 is of the saints of this dispensation alone since Pentecost (to such only applying the expression—”dead in Christ), that will be the beginning of the first Resurrection, which will not reach its final stage until Revelation 20: 4, where the Resurrection of more than one category of saints is indicated, of which we read in verse 5, “this is (i.e., completes), the first Resurrection.” This will no doubt include the Old Testament saints. To conceive of Old Testament saints however, being included in the first Resurrection, at the same time as the Church, is very difficult and indeed impossible. How could such be caught away to meet the Lord in the air along with the Church? In that case there would be two distinct companies, each in a distinct relationship with the Lord.