Hello...
I believe that we can be a Christian AND an American...just like I can be a father/husband and a son/brother.
The same man who said:
[b]But our citizenship is in heaven[/b], and from it we await a Savior, the Lord Jesus Christ, who will transform our lowly body to be like his glorious body, by the power that enables him even to subject all things to himself. (Philippians 3:20-21)
...also said...
25 And as they bound him with thongs, Paul said unto the centurion that stood by, Is it lawful for you to scourge a man that is a Roman, and uncondemned?26 When the centurion heard that, he went and told the chief captain, saying, Take heed what thou doest: for this man is a Roman.
27 Then the chief captain came, and said unto him, [b]Tell me, art thou a Roman? He said, Yea.[/b]
28 And the chief captain answered, With a great sum obtained I this freedom. And Paul said, But I was free born.
29 Then straightway they departed from him which should have examined him: and the chief captain also was afraid, after he knew that he was a Roman, and because he had bound him.
Acts 22:25-29
Paul stated emphatically that he was a Roman citizen. Yet, he was the apostle that took the Gospel to the Gentiles throughout the "Roman world."
Our allegiance, of course, is to God first. However, God has, in His good purpose, allowed us to be born in the nation of our temporary citizenship. I can do the work of an evangelist in this temporary citizenship even as I hold a secular job in order to take care of the needs of my family, the poor and those in the Body of Christ. Ultimately, my desire as a Christian in America is not that people sing [i]God bless America[/i] -- but to get people in America to choose to bless God.
Personally, I see nothing wrong with paying my taxes...driving on roads paid for by taxes...or petitioning elected officials in the government (or even unjust judges) about how they might better spend those taxes. I do not believe that this is "unspiritual" (in a sinful sense of the word) any more than it is a civil duty as I realize that God raises up nations, governments and principalities as a "minister of God to thee for good" (Romans 13:4-5).
There is a danger of making an idol out of political systems...or political parties. However, there is also a danger of raising a voice in error too. We need to pray to God for the wisdom on when and how to speak or recognize such things. After all, we are pilgrims and ambassadors of God to this temporary world.