Because the Church isn't present during the tribulation. That's why it's not mentioned. Pretty much a no-brainer.
The lack of the bride of Christ not being in Revelation....but rather at the marriage supper of the lamb is just one of many reasons that show the pre-tribulation rapture.
You want to be a tribulation martyr for all the wrong reasons.
The Pretrib argument relating to the non-mention of the word “Church” after Revelation 3 falls apart when you consider the fact that the word “Church” (speaking of all the elect) is not found anywhere in the whole book of Revelation. All references are to local churches.
The word ecclesia is also not found anywhere in the New Testament books of Mark, Luke, John, 2 Timothy, Titus, 2 Peter, 1 John, 2 John and Jude, yet the Church is undoubtedly the recipient of these inspired gospels and epistles and is continually referred to under many varying descriptions throughout them. Like the whole book of Revelation, these books use varying descriptions of the Church of Jesus Christ such as “saints,” “elect,” “redeemed,” “brethren” and “servants.”
Moreover, the word ‘Church’ is also not used in relation to the overall body of Christ in Romans, 2 Corinthians, 1 Thessalonians, 2 Thessalonians, Philemon and I Peter, but is only used in the context of the local visible gathering of God’s people, a number that quite often included professors and false-professors alike. However, the true Church – the body of Christ – relates solely to Christ’s blood-bought alone.
If the Pretrib logic is correct, and if its adherents are consistent, then the Pretribber must believe that the aforementioned New Testament books have absolutely no relevance whatsoever to the Church of Jesus Christ in this day of grace, but are rather only applicable to the Jews in a supposed seven-year tribulation period? Ironically, the one gospel that the Pretribs contend is written exclusively to the Jews, and has therefore an important relevance to them in the Great Tribulation, is the only gospel that mentions the Church – Matthew. Even then, it is worth noting, we see no mention of the word Church after Matthew 18. Does this mean that Matthew 19-28 relates specially to the tribulation period after the supposed secret rapture?
Notably, in the other New Testament books that do use the word “Church” in relation to the whole body of Christ, we find only one reference in Galatians, Philippians and James and only two verses in Matthew, Colossians and Hebrews. In the remaining books we have no mention of the Church after Acts 20:28, 1 Corinthians 15:9, Ephesians 5:32, 1 Timothy 5:16 and 3 John 1:10. Do all these particular passages reveal the actual demarcation line between the so-called Gospel age and the supposed Church-free Great Tribulation period?