Helaman 5

I'm sure as Mormon searched the records of Helaman, amongst all the counsel that Helaman gave to his sons Nephi and Lehi for -

"...he did teach them many things which are not written, and also many things which are written," (Book of Mormon | Helaman 5:13)

...that Mormon stressed Helaman's charge to "remember".

It was in remembering that Helaman reminded his sons, which taught pure doctrines of repentance -

"O remember, remember, my sons, the words which king Benjamin spake unto his people; yea, remember that there is no other way nor means whereby man can be saved, only through the atoning blood of Jesus Christ, who shall come; yea, remember that he cometh to redeem the world." (Book of Mormon | Helaman 5:9)

But then he follows with the conditions of salvation -

"...remember also the words which Amulek spake unto Zeezrom, in the city of Ammonihah; for he said unto him that the Lord surely should come to redeem his people, but that he should not come to redeem them in their sins, but to redeem them from their sins.
11 And he hath power given unto him from the Father to redeem them from their sins because of repentance; therefore he hath sent his angels to declare the tidings of the conditions of repentance, which bringeth unto the power of the Redeemer, unto the salvation of their souls." (Book of Mormon | Helaman 5:10 - 11)

I specifically note the doctrine that the Savior "hath power given unto him from the Father to redeem them from their sins because of repentance". That is why He cannot save them in the sins. The "Father" requires the condition of repentance -

"...remember, remember that it is upon the rock of our Redeemer, who is Christ, the Son of God, that ye must build your foundation; that when the devil shall send forth his mighty winds, yea, his shafts in the whirlwind, yea, when all his hail and his mighty storm shall beat upon you, it shall have no power over you to drag you down to the gulf of misery and endless wo, because of the rock upon which ye are built, which is a sure foundation, a foundation whereon if men build they cannot fall." (Book of Mormon | Helaman 5:12)

Don't be fooled when the natural man suggests that confession is all that is required. The truth is, man must repent to receive redemption.