About believing in God and the possibility of Him not existing well for me that isn't a question, there is absolutely no amount of dread within me thinking about the possibility of God not existing because I know He does... Now of course I do not have a perfect knowledge of this because I have not seen Him or met Him. But I have faith and I feel His love and His spirit and have seen His miracles all around me... U might ask "well how do you know?" , I just do. I couldn't explain to you what salt tastes like if you asked (besides salty) but I know what it tastes like.... it's kind of the same with how I know God exists, I can't exactly explain it but I just know, I have tasted of His spirit and His love for me and I just know... as funny as that may sound.
We also have what is called "The Book of Mormon" which we believe is an ancient record containing the teachings of Christ in the ancient Americas. We believe that around 400 BC (i believe around the time of Jeremiah) that a group of people from Jerusalem were called of God to leave and travel into the wilderness where they ended up building a boat and sailing to the ancient Americas (their decsendants being american indians). On the American Continent they had Christ's church and His teachings just as they did in Israel. On this contitnent Prophets were called and taught just like in the Bible... The Book of Mormon is another testament of Jesus Christ and a companion to the Bible. We believe that it was found written upon golden plates by a young boy named Joseph Smith in the 1800's. Joseph, through God's help, translated the Book and restored Christ's church on earth, he was also called to be a modern day prophet and receive direct revelation from God. Since Joseph is obviously dead there has been many prophets called since him and currently it is the before mentioned President Hinkley.