I want to respond to an issue that often comes up. Pretribulationists argue that since certain “mysteries” were absent from the Old Testament but revealed in the church age, therefore, this is evidence for the church/Israel temporal separation. But this hermeneutic principle does not work because there are several biblical truths that clearly reveal mysteries happening in the present church age that will extend and become fulfilled during the future seventieth week of Daniel, which indicates that the church age extends into the seventieth week:
For if you were cut off from what is by nature a wild olive tree, and grafted, contrary to nature, into a cultivated olive tree, how much more will these natural branches be grafted back into their own olive tree? For I do not want you to be ignorant of this mystery, brothers and sisters, so that you may not be conceited: A partial hardening has happened to Israel [the church age] until the full number of the Gentiles has come in. And so all Israel will be saved, as it is written: “The Deliverer will come out of Zion; he will remove ungodliness from Jacob. And this is my covenant with them, when I take away their sins [at the completion of the seventieth week].” (Rom 11:24–27; cf. 1:1–2; 16:25–26; Col 1:26–27)
For the mystery of lawlessness is already at work [the church age]; only he who now restrains will do so until he is taken out of the way [at the midpoint of the seventieth week]. (2 Thess 2:7)
Jesus answered them, “To you it has been granted to know the mysteries of the kingdom of heaven [the church age] . . . . and the harvest is the end of the age; and the reapers are angels. So just as the tares are gathered up and burned with fire, so shall it be at the end of the age [this judgment at the end of the age begins during the seventieth week].” (Matt 13:11, 39–40 NASB; cf. 24:14; 28:20!)
But in the days when the seventh angel is about to blow his trumpet, the mystery of God [that has been happening during the church age] is completed [at the completion of the seventieth week], just as he has proclaimed to his servants the prophets. (Rev 10:7)
On her forehead was written a name, a mystery: ‘Babylon the Great, the Mother of prostitutes and of the detestable things of the earth.’ (Rev 17:5; cf. 17:5).
Regarding this last instance of a mystery, there is a link between Babylon the Great’s persecution and the Bride. Babylon is said to be responsible for the martyrdom of many saints (Rev 18:24—19:2), who are identified as part of the Bride (Rev 19:6–9). And in Rev 13:7 the saints are described with the status of suffering as the object of persecution by the Beast: “The beast was permitted to go to war against the saints and conquer them. He was given ruling authority over every tribe, people, language, and nation” (cf. Dan 7:21–22!). The saints are later described as the Bride of Christ in the privileged status of participating in the wedding celebration in Rev 19:7–8: “‘Let us rejoice and exult and give him glory, because the wedding celebration of the Lamb has come, and his bride has made herself ready. She was permitted to be dressed in bright, clean, fine linen’ (for the fine linen is the righteous deeds of the saints).” Thus, the mystery of Babylon the Great and its activity of killing members of the “Bride” will take place while the church remains on earth during the seventieth week of Daniel.
In summary, all of these instances of mysteries demonstrate that their realization occurs during the church age and extend into and become fulfilled during the seventieth week of Daniel, which indicates that the church age itself continues to extend into the seventieth week. This is, therefore, another thread of evidence that supports the notion that God will be active with the church alongside Israel during the seventieth week.
 E.g. Walvoord, Rapture Question, 1st ed., 38–39. The Greek word mystērion is defined as: “the content of that which has not been known before but which has been revealed to an in-group or restricted constituency—‘secret, mystery.’ hymin dedotai gnōnai ta mystēria tēs basileias tōn ouranōn ‘the knowledge of the secrets of the kingdom of heaven has been given to you’ Mt 13:11. There is a serious problem involved in translating mystērion by a word which is equivalent to the English expression ‘mystery,’ for this term in English refers to a secret which people have tried to uncover but which they have failed to understand. In many instances mystērion is translated by a phrase meaning ‘that which was not known before,’ with the implication of its being revealed at least to some persons” (Louw and Nida, Greek-English Lexicon).
 The following kingdom illustrations refer to the church age period when the gospel is proclaimed: sowing seeds (Matt 13:3–9, 18–30; cf. 36–43); the mustard seed growing into a tree (Matt 13:31–32); leaven in flour (Matt 13:33); a treasure (Matt 13:44); a pearl of great value (Matt 13:45–46); good and bad fish (Matt 13:47–50).
 There are other similar mysteries that extend the present church period into the future during Daniel’s seventieth week (e.g. Col 2:2–3; 1 Tim 3:16; Eph 1:9–10; cf. Gundry, Church and the Tribulation, 13–14). In addition, Paul describes the mystery of the resurrection (1 Cor 15:51–52) as the last generation of the church not having to die, since they will receive their new bodies as they will be alive when Christ returns. Paul locates this event at the parousia (1 Cor 15:23; cf. 1 Thess 4:15). And Jesus places the parousia after (not before) the great tribulation (Matt 24:27; cf. 24:28–31).