The belief in only one god is monotheism.
The word "imaan" means "belief in God," while "Islam" means "security through submission to God."
I think you mean monotheism. That simply means the belief in one God. Mono means "one" and theos is the greek word for God. Thus monotheism means "one God".
Ism: represents Belief In or Commitment To. Theism: "theos" means god or God; "a belief in or commitment to God" Pan-theism: "pan" means All, Everywhere; "a belief or commitment to a god being everywhere or in all things" A-theism: "a" means Not, Negative-of; "a belief that there is no God" Mono-theism: "mono" means One, Single, Undivided; "a belief that there is only one God"
Atheism.
when someone has belief of more than 1 god it is called polytheism. polytheism is a word that has the definition of this noun means the belief or worship of more than 1 god.
Sikh's belief in one God, they call God Waheguru means 'Wonderful Lord'.
Christian
The word for a belief or religion having one god is "monotheism".
A belief is a strongly held opinion: Opinions.Convictions
theistic means has qualities of a god or believing in god, theism means the belief in god
Monotheism is the belief in only one God.