The following link and quote are from a known LDS teacher Mark A. Brown (who also writes for lds.org). Here, he teaches that Jesus, like all humans, were spiritually born in the premortal world before they were born in the physical (mortal) world. The Bible teaches that Jesus is eternally God the Son and that "in the beginning was the word, and the word was with God, and the word was God." Jesus said, "I and the Father are one," and, "If you have seen me, you have seen the Father." Jesus also freely and openly accepted worship from his followers. Nothing was made that was not made by him. Jesus identified himself as "I Am". Mormons reject this.
What do Mormons Believe about the Birth of Christ?
"When we speak of ourselves being the children of God, we mean that we are all
spirit children of God. In other words, in the premortal world each of us was begotten and born as a spirit child of our Heavenly Parents (The Family: A Proclamation to the World). In this sense, our birth was no different from Jesus’s birth because he was also a spirit child of God and was the Firstborn (DC 93:21)." Mark A. Matthews.
Matthews is saying that before his physical life on earth, he was spiritually born in heave. (This is one example, let me know if you need more). "Heavenly Father" had spiritual sex with heavenly mother. That is contrary to what the Bible teaches. By the way, you dismiss the book of Mormon as being historical (and I agree). If that is the case, why do you believe any of it?
I agree, Mormons demonstrate virtuous behavior. So do a lot of Buddhist and Muslims, but that doesn't make them Christian. Here is the thing: behavior doesn't get us to heaven, believing God's Word gets us to heaven. And Jesus is God's Word!