Where did the custom of dancing with flags during worship originate? I'm trying to get some background about the custom of dancing with flags during worship. I come from eastern Europe and I have seen many "trends" that came from the west (especially from charismatics). When did the churches start to dance with flags, and why?

Here is a concrete example.
In American Christianity, specifically black or African American churches, "praise dancing" is a cultural norm practiced all over the United States, generally in more progressive churches.  It is also referred to as Liturgical Dance(a).

Generally, the practice involved playing gospel ballads or other popular black gospel music from contemporary black gospel artist.  Brightly colored flags, scarves, and shawls are used and artist, usually young women, dance using ballet-like movements, in unison with the music being played as a form of worship and praise toward God.

Historically, Liturgical Dance is ancient, tracing back to even ancient Israel as noted in passages like 2 Samuel 6, albeit, this is David and many did condemn him for his expressive worship.  However, in the middle ages, according to professor Paul Dilley at the University of Iowa, the Dance of the Savior, a liturgical dance, was probably used in some "churches and martyr shrines".  In addtion, Dilley states that a "dance scene in a Coptic text from the Qasr el-Wizz monastery suggests that ritual dance enjoyed a place in established, orthodox Christianity..."

Regardless, it is probably not possible to establish an exact reference to the beginnings of such practices in the American church.  Theologically, it is forbidden by some denominations, including some that are primarily African American, because it is consider too liberal or sensual(b).



(a) Based on my personal experience growing up and being involved in the Progressive Baptist Convention and other independent and other affiliated black churches primarily in and around the Washington DC Metropolitan Area. 

(b) As an example of why this practice is not accepted, see There is Never a Good Reason For Liturgical Dance