"Mormons follow the teachings of Joseph Smith, believing that Jesus is one god among many gods; they do not believe that He is the one-and-only God.
Mormonism further deviates from Christianity in the belief that the Father was once a man on another planet who elevated himself to divinity (Teachings of the Prophet Joseph Smith, sel. Joseph Fielding Smith, 1976, pp. 345–46). God the Father had a father, who also had a father, etc. This contrasts sharply with the Bible’s revelation of the eternal and transcendent God who is the uncreated Creator of all things. Additionally, Mormonism posits that the Father has wives, and that all humans on Earth are children of a Heavenly Mother who mated with the Father. Jesus is the eldest child of those unions (Mormon Doctrine, pp. 129 and 516)."
"Latter-day Saints are a modern group espousing the ancient heresy of Arianism, the belief that Christ was a created being. The disagreements between Mormonism and orthodox Christianity are not secondary issues that we can agree to disagree on. Mormon beliefs challenge foundational notions about God, Jesus, and Scripture and cannot be reconciled with the teachings of the Bible."
Source: https://www.gotquestions.org/Christians-Mormons-same-Jesus.html
Mormons believe in the Book of Mormon, adding to the word of God.
The Bible says in Revelation:
"I testify to everyone who hears the words of the prophecy of this book: if anyone adds to them, God will add to him the plagues which are written in this book; and if anyone takes away from the words of the book of this prophecy, God will take away his part from the tree of life and from the holy city, which are written in this book." (Revelation 22:18-19)
https://www.bible.com/bible/100/REV.22.NASB1995
God does not add more to His words in the Bible.
Everyone needs to believe in Jesus (His atoning death to pay for our sins on our behalf), repent, and follow Him.