Jesus asked his disciples "whom do men say that I the Son of man am?" and the disciples told him what other people were saying. Then, Jesus asked them, "but whom say ye that I am?". Then Simon Peter answered and said, "Thou art the Christ, the Son of the living God."

Simon Peter knew through personal revelation that Jesus was the Christ. What other people said about Jesus didn't sway his testimony. 

Today, there are libraries of literature, blogs, podcasts, websites, and YouTube videos that criticize the Church of Jesus Christ of Latter-Day Saints, the prophet Joseph Smith, The Book of Mormon and so on. Their purpose is to destroy faith. Reading or listening to this material is like asking the leaders of Iran or North Korea to tell you the truth about the United States of America. It's going to be negative, biased, and untrue. 

We can know what is true by studying reliable sources and asking God our questions. The witness we receive from the Holy Ghost can--like it did for Simon Peter--give us confidence in what we know to be true, regardless of the opinions of others.