It is not the obligation of the Christian pastor or of the local church to foster love of country. While the Christian can be grateful for her nation (land, people, heritage) because there is always created goodness even in broken places and people, her loyalty is always first to the kingdom of heaven—to this world made a New Creation—and not to any temporal state.
Most Christians that have lived since Pentecost have lived under governments that conflict with their loyalties to Christ, and no state in history is a perfect reflection of God's rule.
When it comes to children, the church can encourage gratitude for the created goodness of one's people and respect for a nation's laws and institutions—when they are just and good—while instilling a primary loyalty to the New Creation.
Pledges and flags and patriotism are fine as far as they go and can be beautiful when they do not involve embracing tyranny or oppression or slavery or conquest but the Christian has deeper spiritual commitments and a higher materiality to which his heart and body are bound.
The church is not the location for instilling national pride but rather for the worship of the creative power that is revealed in the humility and powerlessness of Jesus Christ, the man who alone is God, and by which the worlds were framed. All things are held together by his divine charity. It is his nation to which the people of God belong as to a peculiar country.
This is why at the beginning of National Socialism in Germany Dietrich Bonhoeffer could pray that the state of Germany might die so that the nation of Germany might experience resurrection.
I sometimes now wonder if we have not gotten perilously close to the same circumstance in America, where the church has to have the courage to pray that our state might experience a kind of death in order that all its people, the land, and the best created goodness of its place in history—these things that Christians can rejoice in—might experience resurrection.
To the extent that the Christian has wedded himself to any form of government in the world he will have to die to his patriotic idea of the state in order to inherit the kingdom of heaven.