I am not surprised that comparatively few people join the Church from among the large number on whom the missionaries call. There is no faith. On the other hand, I am amazed that so many do. It is a marvelous and wonderful thing that thousands are touched by the miracle of the Holy Spirit, that they believe and accept and become members. They are baptized. Their lives are forever touched for good. Miracles occur. A seed of faith comes into their hearts. It enlarges as they learn. And they accept principle upon principle, until they have everyone of these marvelous blessings that come to those who walk with faith in this, the Church of Jesus Christ of Latter Day Saints.
It is faith that is the converter. It is faith that is the teacher.
It is that mysterious, wonderful manifestiation of faith that brings reassurance, certainty, and it comes as a gift from God. It is only through faith that we may know the truth of all things. Faith leads to the Holy Spirit, which bears witness of Christ and all things good. And faith is needed for everyday trials - whether it be our mission, our tithing, obeying the word of wisdom. Hold to your faith and ye shall prevail. For further reading, I would recommend reading Alma 32 and James 2:26.