Cultural: The rapidity with which the captured land fills with Lamanites suggests that the Lamanite expansion is partially related to population pressures. Even with such pressures, however, it is unlikely that there would have been an expansion of population that rapid. It is also quite unlikely that the Nephite removal would have removed all of the nominal Nephites, creating a population vacuum into which Lamanites entered. The most probable scenario is that there were large numbers of previous Nephites who actively defected, and many who passively defected. Many of the farmers on their land would have stayed in place and become Lamanites because of the change in the political attachment of the lands.
In the ancient world, there was a tight connection between the religion of a people and their rulership. For many, a change in ruler and a change in religion went hand in hand, and if a new god was powerful enough to conquer, it was powerful enough to worship. In Mesoamerica there was a long tradition of accepting localized deities and placing them under the symbolic overseership of the deity of the conquerors. The Aztec tribal deity Huitzilopocthl was powerful in battle and dominated the spread of the religions, but many of the localized deities were taken into the heartland of the Aztec empire to be worshipped there. In this way the local attachment to their gods was not broken, but the subservience of those gods (and their previous government) to the larger empire was symbolically state by the relocation of the deities to Tenochtitlan.