Jesus was in the temple at the time & exposed that they brought a graven image into the house of God during that spat.

edit: IIRC Ceasar is your God was written on the coins.

edit 2: https://www.lewrockwell.com/2010/03/jeffrey-f-barr/render-unto-caesar-amostmisunderstood-newtestamentpassage/ I believe it was this article that changed my perspective on it.

Jesus was in the temple at the time & exposed that they brought a graven image into the house of God during that spat.

edit: IIRC Ceasar is your God was written on the coins.