it seems I also need to do some English lesson 
From American traditional dictionary:
god
god
AHD:[g¼d]
D.J.[g%d]
K.K.[g$d]
n.
God
A being conceived as the perfect, omnipotent, omniscient originator
and ruler of the universe, the principal object of faith and
worship in monotheistic religions.
The force, effect, or a manifestation or aspect of this
being.
Christian Science Infinite Mind; Spirit; Soul; Principle; Life;
Truth; Love (Mary Baker Eddy).
A being of supernatural powers or attributes, believed in and
worshiped by a people, especially a male deity thought to control
some part of nature or reality.
An image of a supernatural being; an idol.
One that is worshiped, idealized, or followed:
money was their god.
A very handsome man.
A powerful ruler or despot.
So, for christian, their god is Jesus
for Buddhist, their god is Buddha