What are we taught about the end of time according to holy Tradition?

In the Didache we read:

“Be watchful over your life; never let your lamps go out or your loins be ungirt, but keep yourselves always in readiness, for you can never be sure of the hour when our Lord may be coming [Luke 12:35; Matt. 24:42].

“Come often together for spiritual improvement; because all the past years of your faith will be no good to you at the end, unless you have made yourselves perfect.

1248 H. E. Panteleimon Lampadarios, The Catechism of the Orthodox Church: Questions and Answers (Greece, 2006): p. 337.

“In the last days of the world false prophets and deceivers will abound, sheep will be perverted and turn into wolves, and love will change to hate [Matt. 24:12] …

“… for with the growth of lawlessness men will begin to hate their fellows [Matt. 24:8– 10] and persecute them and betray them. Then the Deceiver of the World will show himself [Rev. 12:9], pretending to be a Son of God [2 Thess. 2:4] and doing signs and wonders [Matt. 24:24], and the earth will be delivered into his hands, and he will work such wickedness as there has never been since the beginning.

“After that, all humankind will come up for their fiery trial; multitudes of them will stumble and perish, but such as remain steadfast in the faith will be saved by the Curse (cf. Gal. 3:13) [Matt. 24:8–13].

“And then the signs of the truth will appear: first the sign of the opening heavens, next the sign of the trumpet’s voice [Matt. 24:31], and thirdly the rising of the dead – not of all the dead [1 Thess. 4:16–17] …

“… but, as it says, the Lord will come, and with him all his holy ones [Zech. 14:5] . And then the whole world will see the Lord as He comes riding on the clouds of heaven [Matt. 24:30] …”¹²⁴⁹

1249 “The Didache” in Early Christian Writings , trans., Maxwell Staniforth and Andrew Louth (Penguin, 1987) 16: p. 197–198.