Digital Guide: Are Mormons Christian?
Comparing the Differences Between Mormonism & Biblical Christianity
What does Christianity teach about God's family?
The Bible teaches that only true believers have been given the right to become children of God. We are adopted into the family of God. Unbelievers are children of wrath.
Yet to all who did receive him, to those who believed in his name, he gave the right to become children of God.
What does Mormonism teach about God's family?
Mormonism teaches that all people are the literal spirit children of God. They are the product of Heavenly Father and Heavenly Mother. Satan and his demons are also literal children of God who rebelled and were cast out.
Man, as a spirit, was begotten and born of heavenly parents, and reared to maturity in the eternal mansions of the Father, prior to coming upon the earth in a temporal [physical] body.
Teachings of Presidents of the Church: Joseph F. Smith 
Only believers have been given the right to become children of God.
All people are the literal spirit children of God.