A theist believes there is a God who made and governs all creation; but does not believe in the doctrine of the Trinity, nor in a divine revelation.
A deist believes there is a God who created all things, but does not believe in His superintendence and government. He thinks the Creator implanted in all things certain immutable laws, called the Laws of Nature, which act per se, as a watch acts without the supervision of its maker. Like the theist, he does not believe in the doctrine of the Trinity, nor in a divine revelation.
The atheist disbelieves even the existence of a God. He thinks matter is eternal, and what we call “creation” is the result of natural laws.
The agnostic believes only what is knowable. He rejects revelation and the doctrine of the Trinity as “past human understanding.” He is neither theist, deist, nor atheist, as all these are past understanding.