from Russell M. Nelson, "Perfection Pending", Ensign, Nov 1995 (conference address):This progress toward eternal life is a matter of achieving perfection. Living all the commandments guarantees total forgiveness of sins and assures one of exaltation through that perfection which comes by complying with the formula the Lord gave us. In his Sermon on the Mount he made the command to all men: "Be ye therefore perfect, even as your Father which is in heaven is perfect." (Matt. 5:48.) Being perfect means to triumph over sin. This is a mandate from the Lord. He is just and wise and kind. He would never require anything from his children which was not for their benefit and which was not attainable. Perfection therefore is an achievable goal.
So...the mandate of the lord to be perfect, which LDS take very seriously, is for all intents and purposes a mistranslation of the bible. The context of Matthew 5:48 was not the idea of being flawless at all, but rather, 'impartial'/complete/whole, for the behavior prior to the verse (note the conjunction 'therefore') is pointing out all sorts of partial behavior.In Matt. 5:48, the term perfect was translated from the Greek teleios, which means “complete.”... Please note that the word does not imply “freedom from error”; ... In fact, when writers of the Greek New Testament wished to describe perfection of behavior—precision or excellence of human effort—they did not employ a form of teleios; instead, they chose different words.
Lifting the verse out of context has caused lifetimes of needless guilt.
The term 'mandate' as used in English comes from the 'mandatum' in latin, first referring to the only mandate Jesus made in the scripture in John 13:34 "A new commandment [mandatum novum] I give unto you, That ye love one another; as I have loved you, that ye also love one another."