Below is the English translation of the Portuguese text of the Third Secret given by Our Lady to Lucia at Fàtima on May 13, 1917. I have split it into two parts and highlighted bits to show you the similarities I see with passages from the Book of Revelation. I have paraphrased the Bible passages for clarity only.
After the two parts which I have already explained, at the left of Our Lady and a little above, we saw an ANGEL with a flaming sword in his left hand; flashing, it gave out flames that looked as though they would set the world on fire; but they died out in contact with the splendor that Our Lady radiated towards him from her right hand: pointing to the earth with his right hand, the Angel cried out in a loud voice: ‘Penance, Penance, Penance!’.
Revelation 12:1-6,13-16 – The woman wailed aloud in pain as she labored to give birth and the dragon stood before her to devour her child. She gave birth to a son, a male child, destined to rule all the nations with an iron rod. Her child was caught up to God and his throne. The dragon pursued the woman who was given the two wings of the great EAGLE, so that she could fly to her place in the desert, where, far from the serpent, she was taken care of for a year, two years, and a half-year.
Revelation 4:6-8 – Around the throne [of Heaven], there were four living creatures, each with six wings. The fourth looked like an EAGLE in flight. [Isaiah 6:2 – SERAPHIM were stationed above; each of them had six wings.]
Revelation 8:13 – [After the first four Trumpets] Then I looked again and heard an EAGLE flying high overhead cry out in a loud voice, “Woe! Woe! Woe to the inhabitants of the earth from the rest of the trumpet blasts that the three angels are about to blow!”
And we saw in an immense light that is God: ‘something similar to how people appear in a mirror when they pass in front of it’ a Bishop dressed in White ‘we had the impression that it was the Holy Father’. Other Bishops, Priests, men and women Religious going up a steep mountain, at the top of which there was a big Cross of rough-hewn trunks as of a cork-tree with the bark; before reaching there the Holy Father passed through a big city half in ruins and half trembling with halting step, afflicted with pain and sorrow, he prayed for the souls of the corpses he met on his way; having reached the top of the mountain, on his knees at the foot of the big Cross he was killed by a group of soldiers who fired bullets and arrows at him, and in the same way there died one after another the other Bishops, Priests, men and women Religious, and various lay people of different ranks and positions. Beneath the two arms of the Cross there were two Angels each with a crystal aspersorium in his hand, in which they gathered up the blood of the Martyrs and with it sprinkled the souls that were making their way to God.
Revelation 12:17 – The dragon became angry with the woman and went off to wage war against the rest of her offspring, those who keep God’s commandments and bear witness to Jesus.
Revelation 14:13 – “Blessed are the dead who die in the Lord from now on.” “Yes,” said the Spirit, “let them find rest from their labors, for their works accompany them.”