A challenging perspective:
"I know that, had I become a priest, I would not have been able to celebrate Memorial Day or Independence Day Masses in good conscience. And I know that, as a result, I would run into congregational resistance and be reviled by my 'good, patriotic' churchgoers. But, I would remind them, the days are not on the liturgical calendar for, as much as we tend to forget, they are not part of our Christian story of salvation. The ministry of the priesthood, like the ministry of ecclesially-committed theologians, is to proclaim the Gospel, the Church’s alternative story of salvation. It is a story that exposes the lie of imperial mythologies and narratives through the distinctive life of citizens of an empire not of this world, the history-spanning community of 'resident aliens' within the belly of the world’s empires."
The question of how to be "in the world but not of it" always challenges the church. How do we be good neighbors and fruitful "ambassadors" of Christ, while saying "no" to cooptation and "friendship with the world"?
Anglicans come from a "state church" tradition, and have a long history of providing chaplaincy to culture. Even with that available history, I chafe when it comes to preaching on "Hallmark Holidays." An event like Mother's Day can blow the Christ content out of a service, and the people are likely to be just fine with that. The temptation to kitsch and sentiment is strong - you get stroked for indulging.
The practice I currently embrace is to keep the Christian day intact, especially in the sermon content, while including the national or sentimental day in the Prayers of the People. Yesterday was Trinity Sunday, for crying out loud, Christianity's annual focus on the very name and nature of God. That's what we sang about and what I preached - but in the prayer intentions I certainly offered up thanksgiving for those who sacrificed their lives for our freedom (freedom to worship and call on the Trinity included), and for those in the Armed Forces of the nation today. Prayers for peace are always part of the liturgy, and free intercession is invited - I don't control what people want to lift up to God.
The Catholicanarchy piece has many commendable points. But "Peace fellowships" and other church groups often create ideological conditions that limit prayer and artificially tidy up the ambiguities in the difficult distance between sinful humanity and the Holy God. Some Christian peace groups are militant about eliminating military chaplaincies - which to me makes about as much sense as banning prison chaplains to reduce crime or hospital chaplains to improve health.
Yes, we fall into a trap if we uncritically "baptize" the nation or culture. But our theology and spirituality are pretty pathetic if they define God out of whatever aspects of reality we don't like. A quest for ideological purity won't lead people to the joy of the famine-facing prophet, or the world-weary wisdom of the Teacher, or to the peace of Christ, which passes understanding.