I happen to come across a site on net and found some knowldge relevant to the question-:Should kirtan always be done in Raag?
Though it may not be correct to call kirtan
a distinct school
of Indian music, it is certainly a distinct tradition
and a new contribution to sacred Indian music. It uses both the classical Hindustani music and desi
(folk) music for divine praise and glorification, and employs the local idiom and poetic forms so as to intensify its appeal to the masses. Its objective is spiritual inspiration and its medium is the emotional appeal of both pure and popular music. By combining the purity of raga and tala
with correct intonation and feeling, its appeal extends even to highbrow musicians.Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=8657Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=8657
more important than the musical element is the feeling of love and devotion of the disciple. Even the best and perfect melody, unless accompanied by true belief and sincere feeling for God, may be of no avail. According to the Gurus, mere technical perfection of musical rendering and vocal skill is not kirtan.
I hope this may be of some help i just copied and pasted it from the site on net .