Most flags by their very nature assume religious significance. In most countries civil religion mingles with patriotism in some sort of veneration of the flag. Americans have a pledge of allegiance to their flag which invokes the name of God.
The Palio in Siena is not only an annual horse race, it is the ancient flag bearing an image of the Virgin Mary which the competitors seek to display in their local church. The horses are blessed in the churches before the race.
When companies of German Landsknechte were formed, troops swore in the name of the Trinity to observe the terms of service, and the Ensign swore to defend the Colour to the death. If any crime brought reproach to the Company, its Colour could not fly again until the reproach was wiped off either by the acquittal or condemnation of the alleged criminal. Acquittal or the fulfillment of penance was often marked passing the Colour over the individual's head. Flags were thus imbued with powers of absolution.
The sanctity of military standards is often evoked by quoting the Scripture: "They shall be as when a standard-bearer fainteth." (i.e. when the standard falls, the cause is lost). Because of their importance as symbols and the sacrifice of human life that attended their defence, it was inevitable that military standards took on religious significance. Roman standards were the religion of the army, and in camp they were erected on altars. The fact that the Union Jack is composed of the crosses of three saints certainly adds to its religious significance. In the British Army, the presentation of new Colours is considered a solemn religious ceremony. Military regulations provide for Church of England, Presbyterian and Catholic versions of the ceremony depending on the unit (e.g. English, Scottish and Irish), to be officiated by the appropriate clergy. Upon retirement from service the Colours are laid up in the local church or cathedral in another religious ceremony suited to standards which had been consecrated.