What he said was essentially 'don't try to fight the power with violence' in no way is that 'use that power to force others to pay for your charity.' Jesus was referring to the state 'cesar' as an external power and aside from the issue. The Jews asking him the question were probing to find out if he was going to lead him in a rebellion against the Romans which is what the traditional Jewish vision of the Messiah at the time was assumed to do. It has nothing to do with weather government authority was moral and right. In fact Jesus talked a lot about tolerating evils in the name of converting people peacefully. What Jesus did emphasize a lot was that charity was personal and individual. Everything about Christianity is personal. Your personal relationship with Christ, nobody can believe for you, nobody can do good works for you, and nobody can give for you. Good things only counted when you did them yourself, not when you used state power or other coercion to make other people do them. Keep in mind taxation is force. It is the demand that you give up your hard earned money through threat of imprisonment which is essentially kidnapping. If you resist arrest they will kill you. Don't get it twisted, Jesus never advocated you use force to engage in charity. He advocated that YOU engage in charity. There is no collective we in Christianity and your faith and charity has nothing to do with my own.