Analysis of information sources in references of the Wikipedia article "Book of Revelation" in English language version.
[...] the minor Catholic epistles and Revelation continued to be omitted, and are still not included in the canon of the church of the East which was geographically (and from the late-fifth century doctrinally) isolated in the Persian empire.
Zwingli, the Swiss Reformer, said, '[The Book of Revelation] is not a book of the Bible'.
To this day, Catholic and Protestant lectionaries have only minimal readings from Revelation, and the Greek Orthodox lectionary omits it altogether.