But believing in the Jesus of the BIBLE is critical for salvation.
Jesus is God the Father come in the flesh, virgin born.
The Mormon Jesus is the half-brother of Lucifer, born of a union of God and Mary, one of His many wives, which makes God an adulterer and Mary not a virgin.
No one can believe in just any old being they happen to label as Jesus and expect that that's good enough. Only the virgin born Jesus, who is God Himself, sinless, died, buried and was resurrected, the Jesus of the New Testament, is capable of saving anyone. False Jesus's can't save anyone.
Not Biblical. All we know is that she was a virgin prior to the conception of Jesus Christ. Jesus is not the Father, something Jesus himself makes clear.
LDS doctrine doesn't rely on the Bible alone. Here's all we have in the Bible about the conception of Jesus:
Luke 1:31-1:38
31And now, you will conceive in your womb and bear a son, and you will name him Jesus. 32He will be great, and will be called the Son of the Most High, and the Lord God will give to him the throne of his ancestor David. 33He will reign over the house of Jacob for ever, and of his kingdom there will be no end.’ 34Mary said to the angel, ‘How can this be, since I am a virgin [I do not know a man]?’* 35The angel said to her, ‘The Holy Spirit will come upon you, and the power of the Most High will overshadow you; therefore the child to be born* will be holy; he will be called Son of God. 36And now, your relative Elizabeth in her old age has also conceived a son; and this is the sixth month for her who was said to be barren. 37For nothing will be impossible with God.’ 38Then Mary said, ‘Here am I, the servant of the Lord; let it be with me according to your word.’ Then the angel departed from her.
As to method we don't know any more. We do know that Mary did not have sex with her husband until after Jesus was born.
Matthew 1:25 (New International Version)
25 But he did not consummate their marriage until she gave birth to a son. And he gave him the name Jesus.
That's all we know from the Bible. LDS doctrine teaches differently given additional revelation. Believe as you like, but using the Bible alone you cannot surmise beyond what we have as to method of conception for Jesus. All we know is that she was a virgin prior to conceiving Jesus Christ. She couldn't physically remain one after his birth. Joseph consummates the marriage, no mention is made of her continuing virginity and Jesus has siblings.
No one can believe in just any old being they happen to label as Jesus and expect that that's good enough. Only the virgin born Jesus, who is God Himself, sinless, died, buried and was resurrected, the Jesus of the New Testament, is capable of saving anyone. False Jesus's can't save anyone.
True and I presume you mean Mary started as a virgin as she certainly couldn't be one after Christ's birth.
That said, one doesn't have to believe in the Trinity to be saved. That's a Biblical fact.