Spiritual crusades and journeys often require certain standards of behaviour and flags in dreams will often symbolize an idea or principle. Any national flag will signify a degree of patriotism that may be necessary, or possibly the need to be more militant. Now with its connection to international sport, a flag can suggest an opportunity for exhibitionism. A flag in a dream will have the same meaning as a banner - that is a standard or a place round which people with common aims and beliefs can gather. It may represent old-fashioned principles and beliefs. You might like to consult the entry for Banner for further clarification.