The major gods are the most powerful in their domain and have many worshippers throughout the entire world. Their personalities range from pure and benevolent to pitch-black and evil. Most of these gods have many smaller gods under them who rule over the same domain or specific element of it but are weaker or have fewer worshippers.
These gods did not get their positions for free and, especially the gods of smaller domains, sometimes have to relinquish their positions to another who has become more powerful than them or simply does a better job of it.
NOTE: Losing worshippers is the consequence of a god becoming weaker/ less capable in comparison to other gods. Not the other way around.