By Dr. Andy Woods
Sugar Land Bible Church
My previous articles commenced a series on the rapture of the church. We began with the question, "What is the Rapture?" This question can best be answered by noting ten truths about the rapture from 1 Thessalonians 4:13-18 and 1 Corinthians 15:50-58. In previous articles from 1 Thessalonians 4:13-18, we saw that the rapture is an important doctrine and not something that can be marginalized or explained away as a secondary doctrine. We also noted that the rapture is an event that is distinct from the Second Advent of Christ. We further observed that the rapture will involve the catching up of every believer to meet the Lord in the air, and that the rapture will involve a reunion between living and deceased Church-Age believers. We then began to examine several more points from 1 Corinthians 15:50-58. We noted that the rapture will be a resurrection, will exempt an entire generation of believers from death, and will be an instantaneous event. We now move on to our eighth point.
Eighth, the rapture is a mystery. First Corinthians 15:51 says, "Listen, I tell you a mystery: We will not all sleep, but we will all be changed..." (italics added). Note Paul's use of the word "mystery" (or mysterion in Greek). When people read the word "mystery" in the New Testament they have a tendency of importing an English understanding of the word back into the text. Such an anachronistic reading is unfortunate since the word "mystery" means something quite different in English than it does in Greek, which was the original language of the New Testament. In English, "mystery" refers to something obscure, hidden, or something that cannot be made known except through great diligence. For example, if I said I was watching a mystery movie or reading a mystery novel, I would be conveying the idea that I really did not understand who the villain was until the very end of the movie or the last chapter of the book.
However, in Greek, "mystery" simply means a previously unknown truth now disclosed. Romans 16:25-26 captures the biblical meaning of the word mystery when it says, "Now to Him who is able to establish you according to my gospel and the preaching of Jesus Christ, according to the revelation of the mystery which has been kept secret for long ages past, but now is manifested..." Colossians 1:26 similarly indicates, "that is, the mystery which has been hidden from the past ages and generations; but has now been manifested to His saints" (italics added). Vine further explains, "In the N.T, it [mysterion] denotes, not the mysterious (as with the Eng. word), but that which, being outside the range of unassisted natural apprehension, can be made known only by Divine revelation, and is made known in a manner and at a time appointed by God, and to those who are illumined by His Spirit.” 
Thus, because Paul classified the rapture as a mystery in 1 Corinthians 15:51, it is a theological concept unknown in the Old Testament and is barely even hinted at in the Gospels. John 14:1-4 is likely the first reference to the rapture in the entire Bible and represents the only time that Christ referred to this event in His entire ministry.  By contrast, the Second Advent, which will take place at the end of the Tribulation period, is an event spoken of openly not only in the New Testament (Acts 1:11; 2 Thess. 1:6-10; Rev 1:7) but in the pages of the Old Testament as well (Zech. 14:4). In fact, Job, which is the oldest book of the entire Bible, mentions the Second Advent when it says, "As for me, I know that my Redeemer lives, And at the last He will take His stand on the earth" (Job 19:25). My point is that while the Second Advent is openly revealed throughout most of the canon of Scripture from Genesis to Revelation, not so the rapture which is only revealed in the New Testament and does not even become prominent until the writings of the Apostle Paul.
In fact, it is not just the rapture that is a mystery, but so is the entire Church Age. The Church Age refers to the period of time between the church's birthday on the Day of Pentecost in Acts 2 and the conclusion of the church's earthly mission at the point of the rapture. Paul called this entire period of time a mystery (Eph. 3:3-6) that the Old Testament prophets could not foresee (1 Pet. 1:10-11). This age is not even hinted at in any sense in Scripture until the Upper Room Discourse (John 13–17).
Paul's special calling, among other things, was to unfold this unique period of time called the Church Age. Since this age is unknown in the Old Testament and only alluded to briefly by Christ, without Paul's thirteen letters, we would have very limited knowledge regarding the Church Age. What is the church's mission? How are its leaders selected? How is it to be governed? What are its ordinances? How has God equipped its members to serve Him in its local communities? How does it deal with sin in its midst? All of these questions would remain largely unanswered had Paul not been set aside and given the task of filling out mystery realm doctrine for the Church Age. Paul's unique calling may help explain why God allowed him to spend so much time in prison. Unlike modern prisons which are often accompanied with weight rooms and entertainment through colored and cable television, a first-century prison had no such accoutrements. Thus, Paul's multiple imprisonments, whether they be in Caesarea or his two Roman imprisonments, gave him ample opportunity to not only receive revelation from God regarding mystery realm Church Age doctrine but also to record such doctrine in his thirteen letters.
Part of this mystery realm doctrine pertains to how the Church Age will terminate. Thus, God revealed to Paul the ending of the church's earthly mission through the rapture as part of this mystery realm Church-Age doctrine. In 1 Corinthians 15:50-58 and 1 Thessalonians 4:13-18, God revealed to Paul that just as the Church Age began with a miracle resulting in the conversion of three thousand on the Day of Pentecost (Acts 2:41), the Church Age will similarly end with a miracle called the rapture of the church. Because the rapture is part of this mystery realm doctrine given to Paul, it too represents an unknown commodity in the Old Testament.
In sum, not only is the rapture an important doctrine, an event that is distinct from the Second Advent of Christ, an event that will involve the catching up of every believer to meet the Lord in the air, a reunion of living and deceased Church-Age believers, a resurrection, an event that exempts an entire generation of Church-Age believers from death, and an instantaneous event, but the rapture is also a mystery or an unknown truth in prior ages but now openly revealed.
(To Be Continued...)
 W. E. Vine, Vine's Complete Expository Dictionary of the Old and New Testament Words (Nashville: Nelson, 1996), 424.
 For exegetical evidence indicating that Christ alluded to the rapture in this passage, see Andy Woods, "Jesus and the Rapture," http://www.pre-trib.org/data/pdf/Woods-JesusandtheRapture.pdf.