The term "theist" refers to several different types of beliefs that all affirm the existence of a god or gods. Theists stand in contradiction to atheists, who do not believe in the existence of any god, and agnostics who hold the concept of a god loosely, believing that there may be a god.
What is a theist?
Monotheism: the belief that there is only one god. The Bible teaches that there is only one true God, so Christians are monotheists. Other monotheist religions include Judaism and Islam. Each monotheist religion has a unique view of God that differs from the other monotheist religions' views.
Polytheism: belief in many gods. Ancient Greco-Roman culture as well as many ancient Native American tribes had polytheist religions. Anyone who believes in multiple gods or goddesses would be considered a polytheist.
Deism: belief in a creator god. Deists believe that a god/gods created the universe but does not operate in it in any way currently.
Pantheism / Panentheism: god is in all. Pantheists and panentheists believe that god is all and all is god. Pantheism adheres to the idea that a god or gods created the entire material universe.
Autotheism: an autotheist claims that he/she is god or some sort of enlightened one.
According to the Bible, there is one God who created everything (Genesis 1:1). After the Israelites left Egypt, a polytheist nation, God had Moses make it clear to the Israelites that He is one God: "Hear, O Israel: The LORD our God, the LORD is one" (Deuteronomy 6:4; see also Deuteronomy 4:39). The Old Testament asserts that there is only one God and goes so far as to say that only fools say there is no God (Psalm 14:1).
The New Testament develops our view of God as one Triune God—God the Father, God the Son, and God the Holy Spirit. They are three persons contained in one God. All three persons are mentioned at Jesus' baptism when God the Father speaks from the sky and the Holy Spirit descends as a dove (Matthew 3:16–17). In the Great Commission, Jesus instructs believers to: "Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit" (Matthew 28:19). Notice that the word "name" is singular, showing the unique dynamic of the triunity of God.
Christians are a unique type of monotheist because of their belief in one Triune God—the Father, Son, and Holy Spirit (also known as the Trinity)—and because of their belief in Jesus as the risen Lord "because, if you confess with your mouth that Jesus is Lord and believe in your heart that God raised him from the dead, you will be saved" (Romans 10:9).
What is atheism?
What is agnosticism?
Is there a God?
Can the existence of God be proven?
Why should I believe in God?
Truth about Theology