Although Peter witnessed many miracles performed by Jesus, he did not come to a sure knowledge that Jesus is the Christ until it was revealed to him by his Father in heaven. The same is true of each of us. Each of us can receive a testimony that Jesus is the Christ by obeying His commandments, following His example and praying earnestly for the revelatory power of the Holy Ghost to give us a sure knowledge of the truth of all things, all this being done in faith and humility.
You may witness many things,
But sure knowledge comes from God.
Through the Holy Ghost He brings,
The Son, the greatest truth of all!