President Joseph Fielding Smith explained that the mysteries of God are simply those divine principles of the gospel necessary for our salvation that are not understood by the world: “The Lord has promised to reveal his mysteries to those who serve him in faithfulness. … The Gospel is very simple, so that even children at the age of accountability may understand it. Without question, there are principles which in this life we cannot understand, but when the fulness comes we will see that all is plain and reasonable and within our comprehension. The ‘simple’ principles of the Gospel, such as baptism, the atonement, are mysteries to those who do not have the guidance of the Spirit of the Lord” (Church History and Modern Revelation, 2 vols. [1953], 1:43).
The mysteries of God should not be confused with the unworthy pursuit of “mysteries,” or things that God has not revealed. Speaking of this latter use of the word mysteries, Elder Bruce R. McConkie (1915–85) of the Quorum of the Twelve Apostles explained: “There is also a restricted and limited usage of the expression mysteries; it is more of a colloquial than a scriptural usage, and it has reference to that body of teachings in the speculative field, those things which the Lord has not revealed in plainness in this day. It is to these things that reference is made when the elders are counseled to leave the mysteries alone” (Mormon Doctrine, 2nd ed. [1966], 524).