It seems to me that it's "Give to Caesar what is Caesar's and to God what is God's" or something like that.
In other words give your tax money to the worldly government because it is just worldly stuff... and give your soul to God- ie... do God's work.
It's an implication that Christians should act seperately from the corrupt nature of government and not be attached to the corrupt nature of material things so much as to jeopardize being godly to keep money.

Jews and Christians make a lot of references and parables about the innate corruption in politics and power and the necessary seperation of God from that institution in order to keep religion pure. The idea of government being a necessary evil and being seperate from religion is inspired by Judaism, as in many tales show how kings become corrupt and God turns on them regardless of their use of Him.

Of course some justify theocracy through the same stories.
That's religion for ya.

A pacifistic Christian philosophy is that you should not pay taxes because taxes go toward war and violence of the state.

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