In today's Gospel reading (Luke 3:10-18), John the Baptist is preaching to future Christians. He tells the tax collectors not to collect more than what is due. Notice that he does not tell them to stop collecting taxes.
Jesus taught the same notion later when the pharisees asked a trap question about paying taxes. Jesus said (per Luke's Gospel) they should "render to Caesar the things that are Caesar's, and to God the things that are God's". We were made - as physical, embodied beings - for the world. We are meant to support our human government, to do our jobs, to be part of the world - but all without forgetting that we are destined for another.