Beginning with Joseph Smith’s First Vision, the true knowledge of God has been restored in our day.
I am very grateful for the 1838 account of the first vision, in which the Father and the Son appeared to the youthful prophet and again restored to man the true knowledge of God.3

Through Joseph Smith’s First Vision, “the true knowledge of God” was restored.
It should be remembered that the entire Christian world in 1820 had lost the true doctrine concerning God. The simple truth which was understood so clearly by the apostles and saints of old had been lost in the mysteries of an apostate world. All the ancient prophets, and the apostles of Jesus Christ had a clear understanding that the Father and the Son were separate personages, as our scriptures so clearly teach. Through apostasy this knowledge was lost. … God had become a mystery, and both Father and Son were considered to be one unknowable effusion of spirit, without body, parts, or passions. The coming of the Father and the Son placed on the earth a divine witness who was able by knowledge to restore to the world the true nature of God.4
The 1838 account of the [first] vision of Joseph Smith made it clear that the Father and the Son are separate personages, having bodies as tangible as the body of man. It was further revealed to him that the Holy Ghost is a personage of Spirit, distinct and separate from the personalities of the Father and the Son [seeD&C 130:22]. This all-important truth staggered the world; yet, when we consider the clear expressions of holy writ, it is a most astounding and wonderful fact that man could have gone so far astray. The Savior said, “My Father is greater than I;” [John 14:28] and he invited his disciples, after his resurrection, to handle him and see that it was he, for, said he, “A spirit hath not flesh and bones, as ye see me have.” [Luke 24:39.] The apostles clearly understood the distinct entities of the Father, Son, and Holy Ghost, to which they constantly refer in their epistles; and Paul informed the Corinthians of the fact that when all things are subjected to the Father, “then shall the Son also himself be subject unto him that put all things under him, that God may be all in all.” [1 Corinthians 15:28.]
In the 1838 account of the first vision, Joseph Smith beheld the Father and the Son; therefore he could testify with personal knowledge that the scriptures were true wherein we read: “So God created man in his own image, in the image of God created he him; male and female created he them.” [Genesis 1:27.] This was to be understood literally, and not in some mystical or figurative sense.5
1-The Joseph Smith Papers. http://josephsmithpapers.org/paperSummary/history-circa-summer-1832?p=1. Accessed 7/3/14.
2-The Joseph Smith Papers. http://josephsmithpapers.org/paperSummary/journal-1835-1836?p=24. Accessed 7/3/14.
3-The Joseph Smith Papers. http://josephsmithpapers.org/paperSummary/history-circa-june-1839-circa-1841-draft-2?p=2. Accessed 7/3/14.
4-The Joseph Smith Papers. http://josephsmithpapers.org/paperSummary/church-history-1-march-1842?p=1. Accessed 7/3/14.