It is not only evangelical Christians who object to these ideas.

“That’s just not Christian,” said the Rev. Serene Jones, president of Union Theological Seminary, a liberal Protestant seminary in New York City. “God and Jesus are not separate physical beings. That would be anathema. At the end of the day, all the other stuff doesn’t matter except the divinity of Jesus.”

The Mormon Church says that in the early 1800s, its first prophet, Joseph Smith, had revelations that restored Christianity to its true path, a course correction necessary because previous Christian churches had corrupted the faith. Smith bequeathed to his church volumes of revelations contained in scripture used only by Mormons: “The Book of Mormon: Another Testament of Jesus Christ,” “The Doctrine and Covenants” and “Pearl of Great Price.”

Traditional Christians do not recognize any of those as Scripture.

Another big sticking point concerns the afterlife. Early Mormon apostles gave talks asserting that human beings would become like gods and inherit their own planets — language now regularly held up to ridicule by critics of Mormonism.

But Kathleen Flake, a Mormon who is a professor of American religious history at Vanderbilt Divinity School, explained that the planets notion had been de-emphasized in modern times in favor of a less concrete explanation: people who die embark on an “eternal progression” that allows them “to partake in God’s glory.”

“Mormons think of God as a parent,” she said. “God makes the world in order to give that world to his children. It’s like sending your child to Harvard — God gives his children every possible opportunity to progress towards this higher life that God possesses. When Mormons say ‘Heavenly Father,’ they mean it. It’s not a metaphor.”

It is the blurring of the lines between God, Jesus and human beings that is hard for evangelicals to swallow, said Richard J. Mouw, president of Fuller Theological Seminary, an evangelical school in Pasadena, Calif., who has been involved in a dialogue group between evangelicals and Mormons for 12 years and has a deep understanding of theology as Mormons see it.

“Both Christians and Jews, on the basis of our common Scriptures, we’d all agree that God is God and we are not,” Mr. Mouw said. “There’s a huge ontological gap between the Creator and the creature. So any religious perspective that reduces that gap, you think, oh, wow, that could never be called Christian.”