Why is the Apostle icon a shoe with wings? [closed]
The emblem is based on the Talaria, a symbol of the Greek messenger got Hermes. It also stands for traveling quickly over great distances.
In this case, as is backed by the Civilization 6 wiki, the shoes go along with the literal interpretation of the Apostle, acting as a messenger and ambassador for the chosen deity of a given religion as Hermes was known for doing and needing to travel far in order to do so.