A testimony is an honest expression of what you know to be true.
I know, without doubt or reservation, that there is a God, and that He is our Heavenly Father and that He loves us. He loves us so much that He send His only begotten Son to atone for our sins and to show us the way back to Him. He set forth a plan, and I know that the Restoration through Joseph Smith and the coming forth of the Book of Mormon in this dispensation is part of this plan.
I know that the Book of Mormon is true, and that it is a second witness of Jesus Christ. I know that what it contains is true, and that it teaches us, comforts us, and guides us in a world where it can be hard to see where we are going. I know that God communicates with us through the Bible and the Book of Mormon, but also through prophets and apostles. I know that Thomas S. Monson is called of God, and that the apostles and other general authorities in the Church are called and are upheld by the Lord to offer guidance and teaching for our times.
I have witnessed and know the power of prayer and communicating with the Lord. I know that every thought we send heavenward is heard and known by our Father, and that He knows us personally and wants the very best for us. I know that He provides ways for us to be with our families forever, and that His message for us is a message of love.
I know that Heavenly Father and His Son love you, and that you are so very dear to Him. And because He loves you, I love you too.