* Θεός (Theós): This is the most common and general word for "God" in Greek, referring to a deity. It's a good choice in most situations.
* Κύριος (Kýrios): This word means "Lord" and is often used as a title for God, particularly in the New Testament. It emphasizes God's authority and sovereignty.
* ο Θεός (ho Theós): This is the definite article ("the") plus "Theós," meaning "the God." This is used when referring specifically to the one God.
The choice between these depends heavily on context. For a general reference to a god, Θεός is fine. For the Judeo-Christian God, Κύριος or ο Θεός are frequently used.