Section 3(2)(a) in The West Bengal (Prevention Of Violent Activities) Act, 1970
(a)using, or instigating any person by words, either spoken or written, or by signs or by visible representations or otherwise, to use, any lethal weapon -(i)to promote or propagate any cause or ideology, the promotion or propagation of which affects, or is likely to affect, adversely the security of the State or the maintenance of public order; or(ii)to overthrow or to overawe the Government established by law in India.