Belief is the foundation, it drives my behavior and is the reason I want to belong. Frankly, if I didn’t believe, I wouldn’t bother. If I have to pick one of the three, belief is it.
My behavior, however, is the outward manifestation and visible expression of that belief. If my behavior doesn’t reflect my professed belief, most likely that belief is not deeply rooted in my heart and mind. Dieter Uchtdorf said “Faith in Christ will change our thoughts, beliefs, and behaviors that are not in harmony with God’s will.”
Belief propels me toward association with God’s children — in a family, neighborhood, religious congregation, or in the world community. As John Donne, the poet-minister said, “No man is an island.” In the Book of Mormon, in Mosiah 18:8-10, the prophet Alma, teaching about the significance of baptism, says to his people, “as ye are desirous to come into the fold of God, and to be called his people, and are willing to bear one another’s burdens, that they may be light; Yea, and are willing to mourn with those that mourn; yea, and comfort those that stand in need of comfort, and to stand as witnesses of God at all times and in all things, and in all places that ye may be in, even until death, that ye may be redeemed of God, and be numbered with those of the first resurrection, that ye may have eternal life — Now I say unto you, if this be the desire of your hearts, what have you against being baptized in the name of the Lord, as a witness before him that ye have entered into a covenant with him, that ye will serve him and keep his commandments, that he may pour out his Spirit more abundantly upon you?”
For me, belief is the source, and is inextricably linked with behavior and belonging.