Thus he said, The fourth beast shall be the fourth kingdom upon earth, which shall be diverse from all kingdoms, and shall devour the whole earth(καθολική, katholikí̱ -- Catholic [greek for universal]), and shall tread it down, and break it in pieces. And the ten horns out of this kingdom are ten kings that shall arise: and another shall rise after them; and he shall be diverse from the first, and he shall subdue three kings. And he(Pope) shall speak great words against the most High, and shall wear out the saints of the most High, and think to change times and laws(Roman Emperor  Constantine thought to change the Sabbath from Saturday to SUNday rest & worship in 321 A.D.; he was also a SUN worshipper): and they shall be given into his hand until a time and times and the dividing of time. But the judgment shall sit, and they shall take away his dominion, to consume and to destroy it unto the end(Revelation 18:1-10). And the kingdom and dominion, and the greatness of the kingdom under the whole heaven, shall be given to the people of the saints of the most High, whose kingdom is an everlasting kingdom, and all dominions shall serve and obey him. Daniel 7:23-27 KJV

The mark of the beast is Sunday as a holy day; 
The beast organization that has the mark is the Papacy; 
The beast thought to change God's law by changing Sabbath (of the 4th commandment) to Sunday and removing the commandment against the veneration of images. {Daniel 7:25}; 
The beast attempted to change God's times by changing God's holy day from the seventh to the first day of the week and setting the hours for God's holy day from sunset-to-sunset to midnight-to-midnight. {Daniel 7:25}; 
In Bible prophecy, 42 months is 1,260 days and 3½ literal years. {"...until a time and times and the dividing of time." -- Daniel 7:25, Revelation 13:5};
The 3rd angel's message is the warning against the mark of the beast. {Revelation 14:9-12}



4th Commandment: Remember the sabbath day, to keep it holy. Six days shalt thou labour, and do all thy work: But the seventh day is the sabbath of the LORD thy God: in it thou shalt not do any work, thou, nor thy son, nor thy daughter, thy manservant, nor thy maidservant, nor thy cattle, nor thy stranger that is within thy gates: For in six days the LORD made heaven and earth, the sea, and all that in them is, and rested the seventh day: wherefore the LORD blessed the sabbath day, and hallowed it. Exodus 20:9-11 KJV 

Flee out of the midst of Babylon(Roman Catholic Church), and deliver every man his soul: be not cut off in her iniquity; for this is the time of the LORD'S vengeance; he will render unto her a recompence. Jeremiah 51:6 KJV

And after these things I saw another angel come down from heaven, having great power; and the earth was lightened with his glory. And he cried mightily with a strong voice, saying, Babylon the great(Roman Catholic Church) is fallen, is fallen, and is become the habitation of devils(demons), and the hold of every foul spirit, and a cage of every unclean and hateful bird. For all nations have drunk of the wine of the wrath of her fornication(Sunday rest & worship, picking a day as their sabbath, false religions/pagan gods...), and the kings of the earth have committed fornication(worshipping pagan/false gods) with her, and the merchants of the earth are waxed rich through the abundance of her delicacies. And I heard another voice from heaven, saying, Come out of her(RCC), my people, that ye be not partakers of her sins(paganism/false religions, worship & rest on Sunday), and that ye receive not of her plagues. For her sins have reached unto heaven, and God hath remembered her iniquities. Reward her even as she rewarded you, and double unto her double according to her works: in the cup which she hath filled fill to her double. How much she hath glorified herself, and lived deliciously, so much torment and sorrow give her: for she saith in her heart, I sit a queen, and am no widow, and shall see no sorrow. Therefore shall her plagues come in one day, death, and mourning, and famine; and she shall be utterly burned with fire: for strong is the Lord God who judgeth her. And the kings of the earth, who have committed fornication(Sunday rest & worship, picking a day as their sabbath, false religions/pagan gods...) and lived deliciously with her, shall bewail her, and lament for her, when they shall see the smoke of her burning, Standing afar off for the fear of her torment, saying, Alas, alas, that great city Babylon(Rome/Vatican City), that mighty city! for in one hour is thy judgment come. Revelation 18:1-10 KJV

Open your eyes! :(  

Hear, ye deaf; and look, ye blind, that ye may see. Isaiah 42:18 KJV