In the days of Noah the wicked were not saved.
2 Peter 2
4 For if God spared not the angels that sinned, but cast
them down to hell, and delivered
them into chains of darkness, to be reserved unto judgment;
5 And spared not the old world, but saved Noah the eighth
person, a preacher of righteousness, bringing in the flood upon the world of the ungodly;
6 And turning the cities of Sodom and Gomorrha into ashes condemned
them with an overthrow, making
them an ensample unto those that after should live ungodly;
Why would anyone think that those ungodly people had not been warned?
Book of Mormon, Alma 4:5-6
“For behold, if ye have procrastinated the day of your repentance even until death, behold ye have become subjected to the spirit of the devil, and he does seal you his. Therefore, the spirit of the Lord has withdrawn from you and hath no place in you; the power of the devil is over you, and this is the final state of the wicked.”
Mormons claim to believe the Book of Mormon, but it's obvious that they only believe parts of it.