Speaking of taxes, John Piper writes this in his book What Jesus Demands from the World:
It is risky for Jesus to say, “Render to Caesar the things that are Caesar’s.” That puts a high premium on obedience to the demands of Caesar. One of the realities that warrants this risk is that the heart of rebellion is more dangerous in us than the demands of Caesar outside of us. Jesus wants us to see that the danger to our soul from unjust, secular governments is nowhere near as great as the danger to our soul from the pride that kicks against submission. No mistreatment from Caesar or unjust law from Rome has ever sent anyone to hell. But pride and rebellion is what sends everyone to hell who doesn’t have a Savior. Therefore, the subordinate authorities of the world are warranted by God’s will in two senses. On the one hand, he wills that we recognize that these authorities are indeed subordinate and that we glorify him as the only supreme sovereign. On the other hand, he wills that we recognize these authorities as God-ordained and that we not proudly kick against what he has put in place.
Tony Reinke 
Indeed, to render unto God the things that are his is to acknowledge his supremacy both in heaven and on earth, both in his immediate government by the Holy Ghost and in his mediate government through fallible magistrates and clergy. This is what makes it possible and just to render unto Caesar the things that are Caesar’s.
So true. This struggle between the heart of rebellion and the demands of Caesar is alive and well in the church, today. I fear that, in many cases, a sense of battle-ready patriotism has become a measuring stick, so-to-speak, of one’s Christianity.