It doesn't take Laman and Lemuel long to demonstrate a complete lack of faith. They don't believe the message of an angel of the Lord that has just appeared to them. Remarkably, they still fear the power of Laban even though the angel promised that the Lord willdeliver Laban into your hands (v. 29). Nephi commented that their rebellion was because they knew not the dealings of that God who had created them (1 Nephi 2:12).They must not have, if they thought that Laban's men were more powerful that the Creator of heaven and earth.
George Q. Cannon
"After speaking to them the angel departed. We have heard of a good many people who have thought if they could only see an angel, and he should tell them anything, they would believe it, and never afterwards doubt it. Yet here were these two young men who had seen and been spoken to by an angel, and he had scarcely gone when they began to murmur. They did not believe that which the angel had told them." (The Life of Nephi: Faith-Promoting Series, no. 9, p.23 - 24.)