The dispensations is the way that God chose to get himself fame among the nations and to make himself known as the one true God. We know much about him by the way he has dispensed his knowledge of himself practically. Those before the flood could not know him like we do.
Joshua 9:9 And they said unto him, From a very far country thy servants are come because of the name of the LORD thy God: for we have heard the fame of him, and all that he did in Egypt,
Speaking of the tribulation (the Day of the LORD)
15 For, behold, the LORD will come with fire, and with his chariots like a whirlwind, to render his anger with fury, and his rebuke with flames of fire.
16 For by fire and by his sword will the LORD plead with all flesh: and the slain of the LORD shall be many.
17 They that sanctify themselves, and purify themselves in the gardens behind one [tree] in the midst, eating swine s flesh, and the abomination, and the mouse, shall be consumed together, saith the LORD.
18 For I [know] their works and their thoughts: it shall come, that I will gather all nations and tongues; and they shall come, and see my glory.
19 And I will set a sign among them, and I will send those that escape of them unto the nations, [to] Tarshish, Pul, and Lud, that draw the bow, [to] Tubal, and Javan, [to] the isles afar off, that have not heard my fame, neither have seen my glory; and they shall declare my glory among the Gentiles.
20 And they shall bring all your (Israelitish) brethren for an offering unto the LORD out of all nations upon horses, and in chariots, and in litters, and upon mules, and upon swift beasts, to my holy mountain Jerusalem, saith the LORD, as the children of Israel bring an offering in a clean vessel into the house of the LORD.
21 And I will also take of them for priests [and] for Levites, saith the LORD.
22 For as the new heavens and the new earth, which I will make, shall remain before me, saith the LORD, so shall your seed and your name remain.