As far as human deification being a doctrine of the modern Mormon Church, see Gerald N Lund's answer
here in the I Have a Question section of the 2/82 Ensign, which concludes "It is clear that the teaching of President Lorenzo Snow is both acceptable and accepted doctrine in the Church today." Snow, you might recall, coined the couplet, "As man now is, God once was. As God now is, man may be".
Lund's answer shed's light on historical indices--
Lorenzo Snow was baptized a short time later and began his service in the Church. In the spring of 1840 he was called to serve a mission in the British Isles. Before his departure he was in the home of a Church member who was preaching a sermon on the parable of the laborers in the vineyard. (See Matt. 20:1–16.) According to Elder Snow, “While attentively listening to his explanation, the Spirit of the Lord rested mightily upon me—the eyes of my understanding were opened, and I saw as clear as the sun at noonday, with wonder and astonishment, the pathway of God and man. I formed the following couplet which expresses the revelation, as it was shown me, and explains Father Smith’s dark saying to me at a blessing meeting in the Kirtland Temple, prior to my baptism. …
“As man now is, God once was:”
“As God now is, man may be.”
“I felt this to be a sacred communication, which I related to no one except my sister Eliza, until I reached England, when in a confidential private conversation with President Brigham Young, in Manchester, I related to him this extraordinary manifestation.” (Eliza R. Snow, pp. 46–47; italics added. Brigham Young was President of the Quorum of the Twelve at the time.)
President Snow’s son LeRoi later told that the Prophet Joseph Smith confirmed the validity of the revelation Elder Snow had received: “Soon after his return from England, in January, 1843, Lorenzo Snow related to the Prophet Joseph Smith his experience in Elder Sherwood’s home. This was in a confidential interview in Nauvoo. The Prophet’s reply was: ‘Brother Snow, that is a true gospel doctrine, and it is a revelation from God to you.’” (LeRoi C. Snow, Improvement Era, June 1919, p. 656.)
The Prophet Joseph Smith himself publicly taught the doctrine the following year, 1844, during a funeral sermon of Elder King Follett: “God himself was once as we are now, and is an exalted man, and sits enthroned in yonder heavens! … It is the first principle of the Gospel to know for a certainty the Character of God, and to know that we may converse with him as one man converses with another, and that he was once a man like us; yea, that God himself, the Father of us all, dwelt on an earth, the same as Jesus Christ himself did.” (Teachings of the Prophet Joseph Smith, sel. Joseph Fielding Smith, Salt Lake City: Deseret Book, 1938, pp. 345–46.)
Once the Prophet Joseph had taught the doctrine publicly, Elder Snow also felt free to publicly teach it, and it was a common theme of his teachings throughout his life. About ten years before his death, while serving as the President of the Quorum of the Twelve, President Snow incorporated his original couplet into a longer poem. He addressed the poem to the Apostle Paul, who had written the following to the Philippian Saints:
“Let this mind be in you, which was also in Christ Jesus:
“Who, being in the form of God, thought it not robbery to be equal with God.” (Philip. 2:5–6.)
Part of the poem reads:
The boy, like to his father grown,
Has but attained unto his own;
To grow to sire from state of son,
Is not ’gainst Nature’s course to run.
A son of God, like God to be,
Would not be robbing Deity.
(As cited in LeRoi C. Snow, p. 661.)
Numerous sources could be cited, but one should suffice to show that this doctrine is accepted and taught by the Brethren. In an address in 1971, President Joseph Fielding Smith, then serving as President of the Quorum of the Twelve Apostles, said:
“I think I can pay no greater tribute to [President Lorenzo Snow and Elder Erastus Snow] than to preach again that glorious doctrine which they taught and which was one of the favorite themes, particularly of President Lorenzo Snow. …
“We have been promised by the Lord that if we know how to worship, and know what we worship, we may come unto the Father in his name, and in due time receive of his fulness. We have the promise that if we keep his commandments, we shall receive of his fulness and be glorified in him as he is in the Father.
“This is a doctrine which delighted President Snow, as it does all of us. Early in his ministry he received by direct, personal revelation the knowledge that (in the Prophet Joseph Smith’s language), ‘God himself was once as we are now, and is an exalted man, and sits enthroned in yonder heavens,’ and that men ‘have got to learn how to be Gods … the same as all Gods have done before.’
“After this doctrine had been taught by the Prophet, President Snow felt free to teach it also, and he summarized it in one of the best known couplets in the Church. …
“This same doctrine has of course been known to the prophets of all the ages, and President Snow wrote an excellent poetic summary of it.” (Address on Snow Day, given at Snow College, 14 May 1971, pp. 1, 3–4; italics added.)
It is clear that the teaching of President Lorenzo Snow is both acceptable and accepted doctrine in the Church today.