A person who believes in only one god can be called a monotheist. The adjective form, monotheistic, is typically used in terms like monotheistic religions and monotheistic beliefs.

What is a monotheism person?

monotheism, belief in the existence of one god, or in the oneness of God.

Can Christians be monotheistic?

Christians are monotheists; but they believe in three fully divine beings—the three Persons of the Godhead: Father, Son, and Holy Spirit. ... Thus, on the most common way of understanding polytheism, orthodox Christian belief is not monotheistic, but quite clearly polytheistic.