In the New Testament, the common word for God is the Greek word theos. Theos is the basis of the word theology, "the study of God." Theos is used a number of different ways in the New Testament.

It Can Speak of the True God

When the true God is spoken of, the word theos is used.

In the beginning was the Word and the Word was with God [theos] and the Word was God (Jhn 1:1).

It Can Refer to False Gods

The plural form of theos can refer to false Gods.

Indeed, even though there may be so-called gods [theos] in heaven or on earth—as in fact there are many gods [theos] and many lords (1Cr 8:5)

The Greek word translated gods is the plural of theos.

The Word Also Can Mean Humans

Jesus used the word "gods" to refer to human rulers.

Jesus answered, "Is it not written in your law, 'I said, you are gods'? If those to whom the word of God came were called 'gods'—and the scripture cannot be annulled—can you say that the one whom the Father has sanctified and sent into the world is blaspheming because I said, 'I am God's Son'" (Jhn 10:34-36).

Summary

Theos is the common word for God in the Greek New Testament. It normally refers to the true God. However it can also refer to false gods and even humans. The context must determine how it is to be understood.