God the Father. According to the LDS, God was once a man just like us, and his father was a man who became a god by doing good works to earn his salvation and exaltation to God. The LDS God, “Elohim” (called “Heavenly Father” in everyday parlance) has a body of flesh and bones and lives near a star called “Kolob.” Heavenly Father also has wives, but the LDS don’t have an established doctrine about this and it becomes quite difficult to pin them down on the subject. All humans are spiritual children of this god, as are Satan and all the demonic realm. (In the pre-existence before coming on earth, Jesus, Satan and the demons, and humans, were brothers and sisters having the same father.)
A teaching the LDS currently deny was Brigham Young’s theology that Adam was God who came to earth with one of his wives, Eve. Although Brigham Young claimed direct revelation from God as a prophet, this is one doctrine that makes it difficult to get acceptance so it has been discarded.
The Bible tells us God is Spirit and not man (Num. 23:19; 1 Sam. 15:29; Isa. 31:3; Hos. 11:9). We also know spirits do not have flesh and bone because Jesus specifically stated as much (Luke 24:36-39). And we know from Scripture that God is eternal, having no beginning or end (Ps. 90:2; Ps. 93:2; Isa. 40:28).
Personally, I prefer a God better than me, not one who fell into sin and then worked his way to godhood.
Jesus Christ. Mormons claim they are Christians because they believe in Jesus Christ as their savior. However when we examine the identity of their Jesus, we will see that he is not the Jesus identified in the Bible. One can call a dandelion a rose, but it remains a dandelion nevertheless. So let’s look at the differences:
The Mormon Jesus:
A literal son (spirit-child) of a god and his wife
The elder brother of all spirits born in the pre-existence to Heavenly Father
One of three gods overseeing earth
Atoned only for Adam's transgression, thereby providing the opportunity for us to obtain "eternal life" by our own efforts
The literal spirit brother of Satan
Conceived through sexual intercourse between God and Mary.
His death is not able to cleanse some people of all their sins.
The Biblical/Christian Jesus
Uncreated, eternally existing, unique incarnation of God the son.
Unique Son of God with whom none can be compared.
The Second Person of the Holy Trinity
Atoned for our personal sins, thereby securing "eternal life" for us, once we place our trust in his life, death and resurrection.
No relation to Satan, who himself is a created being - an angel who rebelled against God.
Conceived to a virgin Mary by the power of the Holy Spirit.
Jesus' sacrifice on the cross is able to cleanse every person of all their sins.
At this point we can leave the subject as it is, rather than citing the Bible verses and LDS scripture to prove both these identities because I don’t want to spend the time doing so. The point is, that the two are not the same person. So this means either the historical Christian faith is true or else the LDS faith is true. Both identities cannot be true at the same time - it’s called the law of non-contradiction.
A false god and a false Jesus removes the Church of Jesus Christ of Latter-day Saints from the realm of true Christianity.