When a clan has been aligned to a faction, there can be varrying levels of importance of the alignment. In some aligned clans, they may simply prefer members to have the same alignment. Though, for some other clans, if a clan member isn't also aligned to the faction in question, they may receive a temporary or permanent expulsion.
Many clans simply remain unaligned.
Some clans will be only aligned for certain things (such as Castle Wars); however, other clans may choose to be aligned for everything they do, and may have strict rules for following the god. Most clans fit into the middle.