Type that question into a google search and this answer from the LDS Church will be near the top:
Members of the Church of Jesus Christ of Latter-day Saints unequivocally affirm themselves to be Christians. They worship God the Eternal Father in the name of Jesus Christ.
The most important part of this statement is the phrase “God the Eternal Father.” By it, Latter-day Saints mean something very different from their Christian friends. But for this article, we’ll simply address the rationale, which is clear enough: If I worship God in Christ, I can call myself a Christian. But the question remains, is that true?
Worship and Christianity
Many people in the New Testament worshiped God in Christ but were not Christians. In the town of Capernaum, for example, Jesus heals a paralytic to the worship of all: “they were amazed and glorified God” (Mark 2:12). Yet not all in Capernaum were Christ-followers, for Jesus himself says,
And you, Capernaum, will you be exalted to heaven? You will be brought down to Hades. For if the mighty works done in you had been done in Sodom, it would have remained until this day. But I tell you that it will be more tolerable on the day of judgment for the land of Sodom than for you (Matthew 11:23-24).
The cautionary tale of Judas Iscariot should frighten us all. He worshiped God in Christ with the other eleven disciples (Luke 18:43; Matthew 15:31), but inside was a devil (John 6:70). In fact, at the end of the age, everyone will worship God in Christ: “every knee shall bow to me and every tongue shall confess to God” (Romans 14:11; see also Philippians 2:10). Sadly, for those whose names are not written in the Book of Life (Revelation 20:15), this worship has no saving effect.
Clearly, worshiping God in Christ does not make one a Christian. In fact, we can go one step further, for Christianity cannot be defined by any work: “not by works of righteousness which we have done, but according to his mercy he saved us” (Titus 3:5).
But all that begs the question, how does one become a Christian? Let’s answer that question with three points.
First and foremost, Christianity begins with God: “in this is love, not that we have loved God but that he loved us and sent his Son to be the propitiation for our sins” (1 John 4:10). God sent Jesus to become the Christ, that is, the Messiah (John 17:3). As the Christ, he became the sacrificial Lamb who would atone for the sins of the whole world (John 1:29) by a one-time sacrifice of himself at Golgotha (Hebrews 10:12).
Second, those who accept Jesus’s sacrifice for themselves by faith (Ephesians 2:8-9) have peace with God (Romans 5:1), forgiveness of their sins (Ephesians 1:7), freedom from condemnation (Romans 8:1), a glorious inheritance awaiting them in heaven (Ephesians 1:11), and more than their wildest imaginations can fathom (1 Corinthians 2:9).
In other words, when people look into the Bible, they see Jesus, the Christ, who is a Deliverer, Savior, and Friend. They believe these stories really happened, that Jesus factually rose from the grave, and that Jesus’s promises hold true for them. They realize, “Jesus is talking to me! He really wants to save me from my sins.” And then, they accept this gift of salvation that Jesus the Christ is offering.
Third, when someone truly asks Jesus to be their Christ, they will follow Him. “In Antioch the disciples were first called Christians” (Acts 11:26). A disciple is a follower. Following Christ doesn’t make one a Christian anymore than Judas Iscariot’s following made him one, but people who are truly Christians will obey the command of their Lord to follow (Mark 8:34).
Latter-day Saints, in general, want to be regarded as Christians and are often exasperated when other Christians don’t see it their way. I would beg my LDS friends to think of it differently. You see, the opinion of other Christians doesn’t count for much in the court of the Great King, “let God be true though every one were a liar” (Romans 3:4). The King’s ruling is final; His opinion is the only one that counts.
Fortunately, the King has spoken clearly: “we know that a person is not justified by works of the law but through faith in Jesus Christ, so we have believed in Christ Jesus, in order to be justified by faith in Christ and not by works of the law, because by works of the law no one will be justified” (Galatians 2:16).