John received "the Revelation of Jesus Christ" (Rev 1:1) which was composed of "things which must shortly take place" (:1). They are "the words of this prophecy" (:3) pertaining to "the time [which] is near" (:3). Firstly it is addressed to "the seven churches which are in Asia" (:4). John was instructed to "'write the things which you have seen, and the things which are, and the things which will take place after this'" (:19). They apply in a contemporary way locally to those Asian churches and prophetically to "the mystery" (:20) to be unveiled. Some Bible students interpret the seven churches figuratively as dispensational history representing the stages of growth of the church through time. That would mean that Ephesus was the starting point but that they had already "'left your first love'" (2:4). The letters were written because Christ knew believers would have challenges and difficulties and must become "'him who overcomes'" (:7). If you follow this line of reasoning the last-day church would be Laodicea which was "'neither cold nor hot'" (3:15) and said "''I am rich, have become wealthy, and have need of nothing''" (:17). The letter was sent "'to the seven churches'" (1:11) in Asia and would have been circulated for all to read. Each church had individual issues but the overall message would be studied. Of interest to some would be "things which will take place" (1:19) in the "near" (:3) future. For instance, Smyrna was "'about to suffer'" (2:10) persecution to be "'tested'" (:10) and "'have tribulation ten days'" (:10). On the plus side the churches of Smyrna and Philadelphia were the only ones that Christ's revelation had nothing "'against'" (2:4;:14;:20;3:2;:15). But specific warning and counsel apply to each church individually so you can't generalize and apply everything to everyone. For instance, Jesus told Philadelphia, "'Because you have kept My command to persevere, I also will keep you from the hour of trial which shall come upon the whole world, to test those who dwell on the earth'" (3:10). Many prophetically refer to this as when "there will be great tribulation" (Mt 24:21) which defines the Great Tribulation. The church of Philadelphia is supposed to be spared according to some people's exegesis. But Smyrna was told "'the devil is about to throw some of you into prision" (2:10) and they should "'Be faithful until death'" (:10). "'For the elect's sake those days will be shortened'" (Mt 24:22).
Jesus prophesied, "'There will be a great tribulation such as not occurred since the beginning of the world until now, nor ever shall'" (Mt 24:21). Luke records, "'There will be great distress upon the land, and wrath to this people'" (Lk 21:23). One of the elders said, "'These are the ones who come out of the great tribulation'" (Rev 7:14). Jesus told them, "'In the world you have tribulation, but take courage, I have overcome the world'" (Jn 16:33). He "disarmed the rulers and authorities . . . [and] triumphed over them through Him" (Col 2:15). The Bible is a spiritual book, so what is tribulation? James said to regard it as advantageous "when you encounter various trials" (Ja 1:2) because they require faith to be victorious (:3). Peter said to "not be surprised at the fiery ordeal among you" (1Pe 4:12) because then you "share the sufferings of Christ" (:13). Paul said that God's defenses would enable you to "stand firm against the schemes of the devil" (Eph 6:11). He said the conflict was "against the spiritual forces of wickedness in the heavenly places" (:12) and we would need faith to defend against "the evil one" (:16). Jesus prayed that the Father would "'keep them from the evil one'" (Jn 17:15). Satan takes advantage of every opportunity but God said, "'Vengeance is Mine, and retribution'" (Dt 32:35). God doesn't punish every little mistake because he is "compassionate and gracious, slow to anger and abounding in lovingkindness" (Ps 103:8). But "the anger of the Lord burned against Israel" (2Sa 24:1) and then "Satan stood up against Israel" (1Ch 21:1) which "incited David" (2Sa 24:1) "to number Israel" (1Ch 21:1). Moses told Israel that intermarriage would "'turn your sons away from following Me to serve other gods; then the anger of the Lord will be kindled against you and He will quickly destroy you'" (Dt 7:3-4). Eschatologically speaking "destruction will come upon them suddenly like labor pains upon a woman with child, and they will not escape" (1Th 5:3).