Thus they have an idol that they petition for victory in war; another for success in their labors; and so for everything in which they seek or desire prosperity, they have their idols, which they honor and serve.

This quote means that people pray to idols or figures to ask for help with different things. For example, they may pray to an idol to ask for victory in a war, or for success in their work. Basically, these people worship their idols in order to gain success in different areas of their lives.