8 The wind bloweth where it listeth, and thou hearest the sound thereof, but canst not tell whence it cometh, and whither it goeth: so is every one that is born of the Spirit.
President Gordon B. Hinckley said:
“This thing which we call testimony is the great strength of the Church. It is the wellspring of faith and activity. It is difficult to explain. It is difficult to quantify. It is an elusive and mysterious thing, and yet it is as real and powerful as any force on the earth. The Lord described it when He spoke to Nicodemus and said, ‘The wind bloweth where it listeth, and thou hearest the sound thereof, but canst not tell whence it cometh, and whither it goeth: so is every one that is born of the Spirit’ (John 3:8). This thing which we call testimony is difficult to define, but its fruits are plainly evident. It is the Holy Spirit testifying through us.
“Personal testimony is the factor which turns people around in their living as they come into this Church. This is the element which motivates the membership to forsake all in the service of the Lord. This is the quiet, encouraging voice which sustains without pause those who walk in faith down to the last days of their lives.
“It is a mysterious and wonderful thing, a gift from God to man. It overrides wealth or poverty when one is called to serve. This testimony which is carried in the hearts of our people motivates to an impelling duty. It is found in young and old. It is found in the seminary student, in the missionary, in the bishop and the stake president, in the mission president, in the Relief Society sister, in every General Authority. It is heard from those who hold no office other than membership. It is of the very essence of this work. It is what is moving the work of the Lord forward across the world. It impels to action. It demands that we do what we are asked to do. It brings with it the assurance that life is purposeful, that some things are of far greater importance than others, that we are on an eternal journey, that we are answerable unto God. . . .
“It is this element, weak and somewhat feeble at first, which moves every investigator in the direction of conversion. It pushes every convert toward security in the faith. . . .
“Wherever the Church is organized its power is felt. We stand on our feet and say that we know. We say it until it almost appears to be monotonous. We say it because we do not know what else to say. The simple fact is that we do know that God lives, that Jesus is the Christ, and that this is Their cause and Their kingdom. The words are simple, the expression comes from the heart. It is at work wherever the Church is organized, wherever there are missionaries teaching the gospel, wherever there are members sharing their faith.
“It is something that cannot be refuted. Opponents may quote scripture and argue doctrine endlessly. They can be clever and persuasive. But when one says, ‘I know,’ there can be no further argument. There may not be acceptance, but who can refute or deny the quiet voice of the inner soul speaking with personal conviction?”
(“Testimony,” Ensign, May 1998, 69–70.)