More on Moroni's promise

To really understand Moroni's plea, however, is to understand what Moroni's primary concerns were for his readers. If you look at his previous last sermon in Mormon 9, it becomes obvious that Moroni was heavily concerned with the people who would read the Book of Mormon would be people who did not believe in miracles. Here he gives a very similar sermon to that which he gives in Moroni 10:

7 And again I speak unto you who deny the revelations of God, and say that they are done away, that there are no revelations, nor prophecies, nor gifts, nor healing, nor speaking with tongues, and the interpretation of tongues;
8 Behold I say unto you, he that denieth these things knoweth not the gospel of Christ; yea, he has not read the scriptures; if so, he does not understand them.
9 For do we not read that God is the same yesterday, today, and forever, and in him there is no variableness neither shadow of changing?
10 And now, if ye have imagined up unto yourselves a god who doth vary, and in whom there is shadow of changing, then have ye imagined up unto yourselves a god who is not a God of miracles.
11 But behold, I will show unto you a God of miracles, even the God of Abraham, and the God of Isaac, and the God of Jacob; and it is that same God who created the heavens and the earth, and all things that in them are.
12 Behold, he created Adam, and by Adam came the fall of man. And because of the fall of man came Jesus Christ, even the Father and the Son; and because of Jesus Christ came the redemption of man.
13 And because of the redemption of man, which came by Jesus Christ, they are brought back into the presence of the Lord; yea, this is wherein all men are redeemed, because the death of Christ bringeth to pass the resurrection, which bringeth to pass a redemption from an endless sleep, from which sleep all men shall be awakened by the power of God when the trump shall sound; and they shall come forth, both small and great, and all shall stand before his bar, being redeemed and loosed from this eternal band of death, which death is a temporal death.
14 And then cometh the judgment of the Holy One upon them; and then cometh the time that he that is filthy shall be filthy still; and he that is righteous shall be righteous still; he that is happy shall be happy still; and he that is unhappy shall be unhappy still.
15 And now, O all ye that have imagined up unto yourselves a god who can do no miracles, I would ask of you, have all these things passed, of which I have spoken? Has the end come yet? Behold I say unto you, Nay; and God has not ceased to be a God of miracles.
16 Behold, are not the things that God hath wrought marvelous in our eyes? Yea, and who can comprehend the marvelous works of God?
17 Who shall say that it was not a miracle that by his word the heaven and the earth should be; and by the power of his word man was created of the dust of the earth; and by the power of his word have miracles been wrought?
18 And who shall say that Jesus Christ did not do many mighty miracles? And there were many mighty miracles wrought by the hands of the apostles.
19 And if there were miracles wrought then, why has God ceased to be a God of miracles and yet be an unchangeable Being? And behold, I say unto you he changeth not; if so he would cease to be God; and he ceaseth not to be God, and is a God of miracles.
20 And the reason why he ceaseth to do miracles among the children of men is because that they dwindle in unbelief, and depart from the right way, and know not the God in whom they should trust.
21 Behold, I say unto you that whoso believeth in Christ, doubting nothing, whatsoever he shall ask the Father in the name of Christ it shall be granted him; and this promise is unto all, even unto the ends of the earth.

With this in mind, his words in 10:3 should be pretty clear: "Behold, I would exhort you that when ye shall read these things, if it be wisdom in God that ye should read them, that ye would remember how merciful the Lord hath been unto the children of men, from the creation of Adam even down until the time that ye shall receive these things, and ponder it in your hearts." The context that Moroni wanted "these things" to be read in is in the context of the miraculous workings of the unchanging God--the very topic of his sermon that he gives when he has "spoken a few words by way of exhortation unto you" and the very topic that he says that "God shall show unto you, that that which I have written is true."