Appearances of God
The first and most awe-inspiring way God reveals Himself to man is through personal visitations to Prophets and Apostles. God revealed and made Himself known to Abraham in Genesis 17, "And when Abram was ninety years old and nine, the Lord appeared to Abram, and said unto him, I am the Almighty God; walk before me, and be thou perfect. (verse 1)" God stood at that time revealed because He showed His body to Abraham and talked with him as one does with a friend.
"And it came to pass, as Moses entered into the tabernacle, the cloudy pillar descended, and stood at the door of the tabernacle, and the Lord talked with Moses. . . . And the Lord spake unto Moses face to face, as a man speaketh unto his friend. (Ex. 33:9,11)" God spoke to Moses face to face (thus also showing Moses His body) when Moses was in the Mount Sinai.
[April 6 1836 Kirtland Temple]
God was first revealed to Adam in the Garden of Eden. It is written, "And the Lord God commanded the man . . .(Gen 2:16)" God is revealed through commandments to Prophets, like Adam, Noah, Abraham, Moses, Elijah, Christ, Peter, Paul, Nephi, Joseph Smith, Thomas S. Monson, etc. When the commandments of God were heeded by Adam, God was then made known to Adam and his posterity.
God was also revealed to Joseph Smith in 1820. President Smith wrote, "I saw a pillar of light exactly over my head, above the brightness of the sun, which descended gradually until it fell upon me. . . . When the light rested upon me I saw two Personages, whose brightness and glory defy all description, standing above me in the air. One of them spake unto me, calling me by name and said, pointing to the other—This is My Beloved Son. Hear Him! (JS-H 1:16-17)"