The word "monotheism" is made up of two parts, from the Greek. "Mono" is a form of "monos," which means "single, alone" and "theism," which is a form of "theos" meaning "a god." So, "monotheism" literally means "one god." "Theism" is also from the Greek. Over time, "theism" has come to mean "belief in a diety"— coined in the 1670s.
Generally, monotheism is the belief in one God. At the center of Christianity and Judaism, monotheism is exercised in the worship of God (the Father), who is all-powerful, has created the entire universe and is still involved with His creation today.
Within this belief system, God is often seen as a being...
...of unlimited power (omnipotence), unlimited knowledge (omniscience), unlimited extension (omnipresence), and unlimited goodness (omnibenevolence).
These beliefs are supported in the Scripture of the Old Testament of the Bible. In Exodus 3, verses 13 and 14, God gives Moses His name, identifying himself as the God of Israel:
Moses said to God, “Suppose I go to the Israelites and say to them, ‘The God of your fathers has sent me to you,’ and they ask me, ‘What is his name?’ Then what shall I tell them?”
God said to Moses, “I am who I am. This is what you are to say to the Israelites: ‘I am has sent me to you.’” (NIV)
The word "monism"...
...comes from the Greek word meaning alone or single.
It basically means that everything comes from one, single thing. The specific definition is that...
...various things or kinds of things...in the world are somehow reducible to, derivable from, or [explained] in terms of one thing (substantival monism) or one kind of thing (attributive monism).
Originally meaning that everything is either mental or material (from Christian Wolff), today the concept reduces everything to one original and lowest form, and ultimately growing beyond its original "singleness" into something more complicated and/or sophisticated. This is different from "plurism" which states that there are many things or many kinds of things.
Research notes that often, and inaccurately, monism is confused with dualism—something having two natures or "sides," such as good and evil. Monism is, however, not dealing with two natures, but only one. Monism is not "plurism" or "dualism."
In other words, monism is...
...the doctrine that the person consists of only a single substance, or that there is no crucial difference between mental and physical events or properties
Monotheism is the belief in one God. Monism is the belief that everything comes from one source. For "monism," a scientist might say that all life comes from carbon: one element. There is theological reference to God in "monotheism," but in "monism," there is a simplistic philosophy that accounts for the basic nature of all things.