Most people will say they “believe in God” but what they mean by that can vary dramatically.
Some say they believe in a “higher power” which is usually an attempt to explain the existence of the world while avoiding any of the moral duties that follow from traditional understandings of God.
Deists say that God created the world and then left it alone to exist and run its course on its own (not possible).
Other people influenced by New Age ideologies say things like there are “many Gods” (polytheism) or that “the world is God” (“pantheism”).
Mormons believe in contradictory notions of a “caused God” and who is one of an infinite number of others.
Others, who even call themselves “Christians”, hold to all sorts of errors about God. Some say God is limited in His knowledge and actually ignorant of the future (“open theism”).