Personally, I do not stop being an American in the liturgy any more than I stop being a Catholic in the voting booth. My two allegiances are deeply intertwined, with complex interactions. Yes, the care of my soul and spiritual matters take a higher priority than my sense of duty to my country, but I seek to achieve a balance in these things, because I was born here, I live here, and I will die here (unless I find another fiancée in Europe…)
Also, I am proud to be a Knight of Columbus. If you know anything about my Order, you will know that we carefully blend Patriotism (the charism of the Fourth Degree) with the other charisms: Charity, Unity, and Fraternity. We are proud Catholics who also happen to be proud Americans, and we defend both the Holy Father as well as the Constitution and our civil liberties.
So it honestly doesn’t bother me to sing patriotic hymns in the context of the liturgy. I’m not going to draw the pedantic card and say that the recessional isn’t part of Mass anyway - to me, that is a cop-out. Devotional songs such as “God Bless America” or “God of Our Fathers” are appropriate to the liturgy during certain times of the year, and, to me, a good way of giving a nod to an important national holiday without the danger of devoting too much liturgical effort to fervent nationalism.
Furthermore, the bishops, speaking through the USCCB, have designated this time the “Fortnight for Freedom”. It is a very special period of intense prayer, study, catechesis, and public action that all American Catholics should be involved in, for the intention of protecting our religious liberty. The bishops in their wisdom have offered us many materials to further this goal, and my parish has implemented them extensively. We are praying a litany for freedom all day on Tuesdays during Eucharistic Adoration. We have added the St. Michael prayer to the end of Mass. We are using the suggested General Intercessions. All the homilies are focused on catechesis about the important issues facing our nation today. If you stop being an American during Mass and bury your head in the sand, you’re not part of the solution, you’re part of the problem. Stand up for the good of your country and pray that our leaders will come to realize that Catholics cherish both our citizenship and our immortal souls. Listen to our holy priests and bishops as they instruct us on how to form our conscience about the political issues that press upon us in these days. And then go out and take action for the good of the Church, and the good of the country.