Elder John A Widtsoe, and apostle in the Church of Jesus Christ of Latter-day Saints, taught that
“In [God's] temples all are dressed alike in white...the symbol of purity...symboliz[ing] that before God our Father in heaven, all men are equal. The...learned and the unlearned, the prince and the pauper sit side by side in the temple and are of equal importance..before the Lord God, the Father of their spirits. It is spiritual fitness and understanding that one receives in the temple. "Have you ever been to a restaurant, and the person you were with said, at the end of the meal, "Don't worry--I've got it covered."? Wasn't it a good feeling that someone was willing to pay the price of the meal for you? In a much more profound way, we can rest in the comfort of knowing that, if we want him to, Christ's grace, through his atoning sacrifice, has got our past sins covered as well, and we don't have to worry about them anymore.
In Hebrew, the word for atonement is "kaphar", which means “to cover” or “to forgive.” Thus, as we serve in the temple, we are reminded by the symbolic clothing that we wear that we are literally covered and made whole by the grace of Christ.
The importance of sacred clothing was taught to our first parents. Some time after Adam and Eve left the garden of Eden, they learned from an angel that the animal sacrifice they had been commanded to perform was "in the similitude of the sacrifice of the Only Begotten [Jesus Christ] of the Father" (Pearl of Great Price, Moses chapter 5 verse 7). From these animals, coats of skins were made as a covering for our first parents. The angel taught them that the purpose of their sacrifice, as well as the significance of their clothing, was to point them forward to the time when Jesus Christ would come to earth to atone for their--and our--sins.
Wherefore, thou shalt do all that thou doest in the aname of the Son, and thou shalt brepent and ccall upon God in the name of the Son forevermore.In the same way, when we enter the temple, exchanging our "street clothes" for clothes of white, we are reminded not only that we are all children of God, but also that we can become pure because our sins are "covered" or forgiven by the grace of Jesus Christ. What a wonderful reason to dedicate our lives to following his matchless example.