FAIR is a non-profit organization dedicated to providing well-documented answers to criticisms of the doctrine, practice, and history of The Church of Jesus Christ of Latter-day Saints.
Jesus Cristo/Acusações de que os mórmons não são cristãos/Será que a Igreja usa o sinal ou símbolo da cruz
Question: Why don't Mormons use the symbol of the cross?
Latter-day Saints do not object to the cross; they simply do not come out of a historical period or tradition in which its use was common
Some Christians claim that Latter-day Saints are not Christians, and point to the fact that the Church does not usually use the symbol or sign of the cross in decoration, personal jewelry, or architecture.
Latter-day Saints do not object to the cross; they simply do not come out of a historical period or tradition in which its use was common. Given that there is nothing in scripture which mandates the use of the cross as a symbol or item of worship, Latter-day Saints prefer to make their Christian discipleship evident by the conduct and caliber of their lives.
Latter-day Saints have no objection to the symbol of the cross. Historically, the Church's earliest members were not from denominations or traditions who used the cross in their worship. When they joined the Church, these traditions continued with them. Isolation in Utah meant that the Saints were not much affected by the increased use of the cross by American protestants later in the century.
Of this question, Elder Marvin J. Ashton of the Twelve said:
Why don't you have crosses on your buildings of worship? Why aren't your chapels built in the shape of a cross? Why don't you encourage your people to wear and display crosses? What is the Church's policy toward crosses? From Matt. 16:24-25:
Then said Jesus unto his disciples, If any man will come after me, let him deny himself, and take up his cross, and follow me.
For whosoever will save his life shall lose it: and whosoever will lose his life for my sake shall find it.
We in The Church of Jesus Christ of Latter-day Saints, in response to these questions, try to teach our people to carry their crosses rather than display or wear them. 
- Marvin J. Ashton, "Carry Your Cross," BYU fireside address (3 May 1992), 1.