Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened.
Romans 1:21
"It is indeed evident, that it is an evil which has prevailed in all
ages 
— that men have allowed themselves every liberty in coining
superstitions.
The arrogance then which is condemned here is this — that
men sought to be of themselves wise, and to draw God down to a level
with their own low condition, when they ought humbly to have given Him His own glory.
For Paul holds this principle, that none, except through
their own fault, are unacquainted with the worship due to God." Calvin