CHRIST promised, in The Gospel of John, that at His Second Coming, just before The End, He would show people clearly about God.
John 16:25 These things have I spoken unto you in proverbs: but the time cometh, when I shall no more speak unto you in proverbs, but I shall show you plainly of the Father.
He said that just before the Last-Day, when everybody is due to be judged on his/her individual merits, He would come again and publish the Truth of God and enlighten the whole world.
Matt: 24:27 For as the lightening cometh out of the East, and shineth even unto the West; so shall also the coming of the Son of Man be.
This is also described in The Book of Revelation / Apocalypse, chapter 10, where the Angel gives the apostle, John, a little book and when he eats it up (reads and digests its contents) it is bitter in his belly, but is in his mouth sweet as honey (easy to read, but not so easy to digest and do what it says).
Rev 10:7 But in the days of the voice of the seventh angel, when he shall begin to sound, the mystery of God should be finished, as He hath declared to His servants the Prophets. Rev 10:8 And the voice which I heard from heaven spoke unto me again, and said..