Where in The Great Gatsby is an example of an allusion?

The Great Gatsby is more noted for
colors, symbols, and images than allusions, but nonetheless there are
some.

One I can recall is the reference to a man named JP
Morgan. This is a financial guy whose work has now become the bank we know today as
Chase.

Biblical allusions are the most common. The image of
Dr. TJ Eckleburg's eyes are regularly alluded to as if they are God's eyes watching over
what man has done with the creation that He gave to man. This is consistent with the
idea that the narrator finds the East void of God and that has caused great destruction
for society.

In chapter 6, Nick narrates about a younger
Jay:

The
truth was that Jay Gatsby of West Egg, Long Island, sprang from his Platonic conception
of himself. He was a son of God - a phrase which, if it means anything, means just that
- and he must be about His Father's
business.

This
allusion to God is a direct reference to when Jesus uses the same phrase in Luke 2:49.
This was a young Jesus who spoke these words and it seems at an earlier point, Jay had
been connected to God in some way. But in the current time of the book, that is not the
case.