"For I know that God is not a partial God, neither a changeable being; but he is unchangeable from all eternity to all eternity." (Moroni 8:18)
"Now, the decrees of God are unalterable; therefore, the way is prepared that whosoever will may walk therein and be saved." (Alma 41:8)
"For do we not read that God is the same yesterday, today, and forever, and in him there is no variableness neither shadow of changing?" (Mormon 9:9)
Official Mormon doctrine, in contrast, affirms that God is increasing in knowledge. Consider this excerpt from Joseph Smith, Journal of Discourses, volume 6:
"The mind or the intelligence which man possesses is coequal with God himself. I know that my testimony is true; hence, when I talk to these mourners, what have they lost? Their relatives and friends are only separated from their bodies for a short season: their spirits which existed with God have left the tabernacle of clay only for a little moment, as it were; and they now exist in a place where they converse together the same as we do on the earth....There never was a time when there were not spirits; for they are co-equal with our Father in heaven."
What we have here, in plain English, is an example of theological inconsistency in Mormon revelation.
If God is able to increase in knowledge, then it follows that He can make mistakes and thus His commandments are liable to error. The Mormon conception of god is not a god in any meaningful sense of the term.