If we are careful not to share our personal, intimate thoughts, they can remain private. For the most part, we can be assured that no one will be able to pry into our private world. But although we can hide our thoughts from others, we cannot hide our thoughts from God. The Lord your God…is a discerner of the thoughts and intents of the heart (DC 33:1), and there is none else save God that knowest thy thoughts and the intents of thy heart (DC 6:16).
When God shares his power of omniscience with his servants, they are able to wield a great weapon in the cause of truth. Zeezrom, the greatest of their lawyers, is reduced to rubble by the power Amulek and Alma demonstrate. Zeezrom's private world of subtlety and wickedness seemed to be laid bare for all in Ammonihah to examine. How humiliating! And how humiliating it would be for us, at times, if our personal thoughts and wicked intentions were made public. See also Jacob 2:5, Alma 18:16.
Spencer W. Kimball
"Being in charge of the Endowment House, while the Temple was in the process of construction, Heber C. Kimball met with a group who were planning to enter the temple for ordinance work. He felt impressed that some were not worthy to go into the temple, and he suggested first that if any present were not worthy, they might retire. No one responding, he said that there were some present who should not proceed through the temple because of unworthiness and he wished they would leave so the company could proceed. It was quiet as death and no one moved nor responded. A third time he spoke, saying that there were two people present who were in adultery, and if they did not leave he would call out their names. Two people walked out and the company continued on through the temple." (Miracle of Forgiveness, p. 112 as taken from Latter-day Commentary on the Book of Mormon compiled by K. Douglas Bassett, p. 263)