How can Yahweh make this covenant of forgiveness of sins through baptism when this event precedes the atonement that creates such forgiveness? Yahweh can make that covenant because he will create the conditions for fulfilling the covenant. In the Book of Mormon, Yahweh-Christ is God. The God who teaches them and communicates with them is the very one who will become incarnate and sacrifice himself for humanity. He has the ability to make this promise because he will fulfill the requirements of this promise.
Text: The first section of this verse may be momentarily confusing: “For it is I that taketh upon me the sins of the world; for it is I that hath created them.” The antecedent for “created them” appears to be “sins of the world.” Of course, that is not correct. The answer lies in the larger context:
For behold, this is my church; whosoever is baptized shall be baptized unto repentance. And whomsoever ye receive shall believe in my name; and him will I freely forgive.
For it is I that taketh upon me the sins of the world; for it is I that hath created them [those who believe in his name]; and it is I that granteth unto him that believeth unto the end a place at my right hand.
For behold, in my name are they called; and if they know me they shall come forth, and shall have a place eternally at my right hand. (vv. 22–24)
In both verses 22 and 23, the Lord is speaking of the people of his church. Since the context both before and after is the same people, “them” refers to those people. Part of the problem in reading the verse is the punctuation, which was added by the typesetter. I would suggest this more logical punctuation:
And whomsoever ye receive shall believe in my name; and him will I freely forgive, for it is I that taketh upon me the sins of the world. For it is I that hath created them [those who believe in his name] and it is I that granteth unto him that believeth unto the end a place at my right hand.