The dictionary definition of deception says that it is the same as deceit, fraud, or lying. It is making a statement that the person knows is not true or a false statement that is meant to deceive. In all but very extraordinary cases (patriotic spying or where an innocent person could be killed or harmed without the lie, with the intention to protect or do right), this deception is wrong. Forms of it (fraud or perjury, for instance) may be prosecuted by law in most, if not all, countries, but it is also against gospel law. It is in violation of the commandment that the Lord gave to Moses, that we "are not to steal, neither deal falsely, neither lie to one another” (Lev. 19: 11). Paul said in Ephesians 4:25, “Wherefore put(ting) away lying, speak every man truth with his neighbor. . . .” Because lying and deceiving are sins, they are heartily condemned, and "liars, shall have their part in the lake which burneth with fire and brimstone, which is the second death” (Rev.21:8). In Mormon doctrine, liars are sent to the Telestial Kingdom, which is the lowest kingdom, higher only than outer darkness where Lucifer dwells.
God is the example of truth, for he does not lie (“God is not a man, that he should lie. . . .” Numbers 23:19. It is“. . . impossible for God to lie” Hebrews 6:18). Deuteronomy 32:4 says that he is “a God of truth and without iniquity. . . .” Lucifer is the example of deceitfulness and lying, being the Great Deceiver and the Father of All Lies (John 8:44), being “a liar from the beginning” (Doctrine and Covenants 62:6). He's the serpent who “sought also the misery of all mankind. Wherefore he said unto Eve. . . Partake of the forbidden fruit, and ye shall not die. . . .” (2 Nephi 2:18). Lucifer's influence was then found in Eve's son Cain, who, after slaying his brother, lied. In response to God's question, “Where is Abel thy brother?” (Genesis 4:9), Cain replied, “I know not” (Genesis 4:9). Today Lucifer still entices men to become liars (2 Nephi 2:18).
Requisite to Deception
Intention and knowledge are requirements for deception or lying. A person who does not know that he or she is making an untrue statement is not guilty of deception because he or she does not do it with the purpose of deceiving another. What this person has done is to misstate or to state incorrectly or falsely. It's a mistake, not the sin of deception.
Where Mormon beliefs may vary from others is that Mormons also believe that deception can occur without making a statement. A person can deceive another by withholding information necessary for the other person to give informed consent or make his choice, thwarting their free agency. This manipulation of information, in Mormon theology, is akin to Lucifer's tactics. Mormons believe that, in a pre-mortal council in heaven, Lucifer volunteered to be the Savior of this world and wanted to force all mankind to do right, thereby denying man his free agency and the right to choose. This would have resulted in men never being able to become adults spiritually, just as never allowing earthly children to learn right from wrong from their choices would result in their never being able to behave like adults. Therefore, to Mormon thinking, to deceive is to thwart free agency by denying someone the power to choose from his options and consequences.
How to Avoid Being Deceived
Paul says that people who believe in false doctrines “believe a lie” (2 Thessalonians 2:1-12), and Jeremiah 16:16-21 says that people who accept false creeds “have inherited lies.” Clearly to be deceived is not a good thing, so how does a person avoid being deceived, especially about religious doctrine?
The Holy Ghost is the “Spirit of truth” (John 15:26), which “will guide you to all truth” (John 16:13). Mormons believe that any person may receive knowledge from the Holy Ghost, so he or she may judge, with the Holy Ghost's help, the truth of what Mormon missionaries, members, and leaders claim about the Church: that the Church of Jesus Christ of Latter-day Saints is the personal, official church of Christ. After baptism into the Church, new members are given the gift of the Holy Ghost on an ongoing basis to help them avoid being deceived and to stay on "the strait and narrow path."