1 Corinthians 8:4

Concerning therefore the eating of things sacrificed to idols, we know that no idol is anything in the world, and that there is no God but one.

The sophisticated arguments of the "knowledge" party in Corinth are apparent in this. Since idols had no existence in fact, they felt safe in ignoring the popular superstitions regarding them; and Paul allowed the argument to stand, for the moment, it certainly being true that there is no God but one, and that an idol actually had no existence in reality.

However, although Paul did not recognize idols "as having any real existence, even as false deities,"[7] he was "certain that evil spirits and demons exist, and that in reality these were behind the idols and were using them to seduce men from the worship of the true God."[8] (See 10:20.)

No idol is anything in the world ... Of course, the world was full of idols; but, as Wesley said:

Idol here does not mean a mere image; but, by an inevitable transition of thought, the deity worshipped in the image. By this, Paul says that Zeus, Apollo, etc., have no existence; they are not to be found in the world.[9]

Furthermore, Paul does not by such a statement (that they are not in the world) leave room for the thought that they may be anywhere else. The "world" as used here refers to the whole universe.

There is no God but one ... He is the God of Abraham, Isaac and Jacob, the God of the Old Testament and of the Christian scriptures. He only is God in the true sense. He alone may rightfully be worshiped, and that through his Son Jesus Christ our Lord.

[7] John William Russell, Compact Commentary on the New Testament (Grand Rapids, Michigan: Baker Book House, 1964), p. 416.

[8] William Barclay, op. cit., p. 83.

[9] John Wesley, One Volume New Testament Commentary (Grand Rapids, Michigan: Baker Book House, 1972), in loco.