"The purpose of life is to seek truth and to chose to live it," Craig Belnap, LDS.
What is truth?
Truth is something that was, is, and will always be. It is real, it is reality. It doesn't change through time, through changes in technology, through changes in philosophies or perceptions of reality. Truth is how things really are! And God is the author of all truth.
Satan, conversley, is the author of all lies. He wants us to be confused about what truth really is. He wants us to believe that there's no such thing as truth, or that truth can vary from person to person, generation to generation, from culture to culture. That is NOT true!
God does NOT want us to be confused! He wants us to understand him and his teachings - truth. That is why we can trust him, because he's not trying to confuse us. He loves us and wants us to be happy. He knows that understanding anything facilitates happiness and contentment. Confusion, on the other hand, only creates discord and contention, misunderstandings and wars. God doesn't want that! Of course, there will always be differences of opinion, etc - we are all different individuals - but by understanding truth and God, we can understand one another and how to help each other and we can live in peace and harmony.