By God’s actual words

Not by man’s words or man’s summaries of God’s word, but by actual words that came from God’s mouth do men begin to have faith.

Moroni 7:25 Wherefore, by the ministering of angels, and BY EVERY WORD WHICH PROCEEDED FORTH OUT OF THE MOUTH OF GOD, men began to exercise faith in Christ; and thus by faith, they did lay hold upon every good thing; and thus it was until the coming of Christ.